The leader of the Assembly of First Nations says his doctor has ordered him to take time off after a frustrating week of negotiations with the federal government and chiefs from his own organization.

Shawn Atleo, the national chief of the AFN, announced on the organization's website that he's taking a "brief" break, and said Roger Augustine, a regional chief from New Brunswick and Prince Edward Island, will chair the group's national executive meetings while he's away.

Saskatchewan Regional Chief Perry Bellegarde and British Columbia Regional Chief Jody Wilson-Raybould will lead the work on treaty implementation and comprehensive claims, Atleo said in the statement.

Attawapiskat Chief Theresa Spence has been limiting her food intake since Dec. 10, to protest the lack of a meeting with both Prime Minister Stephen Harper and Gov. Gen. David Johnston present. She has been consuming only fish broth, water and herbal tea.

Two supporters have been fasting with her, although Spence's spokesman confirmed Monday that one of them has given up the protest. Jean Sock's mother has cancer and he has to go home to be with her, Danny Metatawabin told CBC News.

Spokespeople for Spence said she was sending her well wishes to Sock as he returns to Elsipogpog, N.B., to be with his "gravely ill" mother.

“We thank Jean for his support, courage and endurance he has shown this past month for our common cause. We pray for the Sock family during this difficult time,” Spence said in a statement.

Spence and Raymond Robinson will continue their hunger strikes in a push for a meeting between First Nation leaders, the prime minister and Governor General.

Atleo recovering from norovirus

Two weeks of long conference calls, late-night meetings and "frustrations" have caught up with him, Atleo said.

"This weekend, my doctor ordered that I take some time now to rest and recover, and I have agreed with my family that I do this now.

"I will see you all very soon and will return re-invigorated and strengthened to work with you to drive this change together with all of you."

Atleo will be away for about 10 days, Augustine told CBC News.

"He'll be back and feistier than ever."

Atleo was ill with norovirus over the holidays and hadn't had time to fully recover, according to an AFN official.

Speaking to Evan Solomon, host of CBC News Network's Power & Politics, Saskatchewan Regional Chief Perry Bellegarde said Atleo's need for time off is probably a combination of the illness and the stress of last week.

"It's probably a combination of both, but he really was fighting that virus and long hours from 6 a.m. in the morning until late at night, your body just doesn't have that time to rest and recuperate, so he needs that time right now ... he needs to take that time so he can get better, come back and work," Bellegarde said.

AFN chiefs split over whether to meet last Friday without Johnston present for the working meeting. Chiefs from Manitoba and Ontario boycotted the meeting, with some raising the possibility of a non-confidence vote in Atleo.

'Difficult days'

Atleo said grassroots First Nations protesters seized the attention of Canadians and of the government last week.

"First Nations citizens have just witnessed one of the most important chapters in our recent history," he said.

Activists at the grassroots level, as well as the AFN and the three hunger-strikers, forced open the door to the offices of the prime minister and the governor general, Atleo added.

"We have a responsibility to work together to push forward our work that relates to each of the eight elements that emerged from our discussions [last] week — on treaty, on comprehensive claims, resource revenue sharing, action to assess and halt provisions of legislation that contravene our rights, on the urgent needs of our communities and justice for our missing women," he said.

"I am proud of the support we received from First Nations citizens and chiefs across Canada, even during the most difficult days."

Speaking in Montreal, Harper said the discussions last week were a good exchange of views, even though the government and aboriginal leaders don't necessarily agree.

"I certainly look forward to further conversations, particularly with the national chief when it's convenient for him to do so," Harper said.

'Not about political opportunism'

One of the chiefs who boycotted last Friday's meeting wrote the prime minister Monday to ask for a meeting with Harper, Johnston and indigenous leaders.

Derek Nepinak, grand chief of the Assembly of Manitoba Chiefs, said Harper is ignoring "the call of the chief who will die for her people."

"Many people are praying for you and hope that you will recognize that ... continuing to apply political strategy and Indian Act policy in this very delicate time will only serve to reinforce the growing dissent in your leadership," Nepinak wrote in a letter published on the Manitoba chiefs' website.

"The Manitoba chiefs' ongoing push to help invoke your higher sensibilities is only an expression of their deep commitment to preserve the life of three people who are loved by so many. It is not about political opportunism or any other political dynamic that compromises truth and understanding."

One of the chiefs who broke from Atleo last week said aboriginal protesters would block major roads and rail lines in Ontario on Wednesday if their demands were not met.

Grand Chief Gordon Peters also threatened to go to international investors and tell them their resource extraction projects are not safe if the government pushes through developments without consent from First Nations.

Recent omnibus budget legislation aimed at streamlining resource projects has been a major irritant for the ongoing Idle No More protest movement. Other Harper government cuts to aboriginal programs and organizations are also concerns.

But part of the Idle No More movement is a criticism of the current First Nations leadership as ineffective in dealing with the needs of their people.