"She's so thin I see her muscles straining through her skin when she cries, and I cannot help.
"I am her mother and I cannot help."
The UN said yesterday that Assad's regime had agreed to allow aid into three besieged towns, including Madaya.
But deliveries were not expected to begin before the weekend and Save the Children said more would die if food and medicine did not reach them immediately.
Of the 31 people who are reported to have died of starvation last month, three were under the age of 1.
Several British MPs were understood to be considering calling for the RAF, which is flying air strikes against Isis (Islamic State) in Syria, to begin aid drops over Madaya.
One resident, Abdullah, said he was surviving on strawberry leaves and had not eaten a full meal in three months.
"We've had many wars in the Middle East, yes, too many wars. But we've never had starvation," he said.
At a local field hospital, a doctor said he treated 230 patients for fainting yesterday alone.
Madaya and Zabadani are the last remaining opposition enclaves along the Lebanese border and observers said a siege is a common regime tactic.
"We've seen it time and time again," said an aid worker. 'The regime uses its military force to starve the people into submission and the suffering is immense.'
Armed groups opposing Assad have used similar tactics in the largely Shia towns of Fouaa and Kefraya.
Few in Madaya can afford what little food is still available on the black market. According to Save the Children, a kilogram of bulgar wheat reached 190 ($418) on Thursday.
At least 10 people have been killed trying to escape. A further eight have lost their legs or feet, returning to Madaya to find no treatment available.
Pawel Krzysiek, a spokesman for the International Committee of the Red Cross, said 50 of its volunteers had been killed since the Syrian war began in 2011.
"But it is urgent that we get through," he said.
"Mothers can no longer lactate - they are malnourished, they don't have health care, they live in the stress and the freezing cold."
Abdullah said: "We are like zombies, like dead people. We are just waiting for our funeral."