My littlest at 2 months of age was found to have a tumor growing on his neck. His weight had slowed every appt after his birth till they found that tumor. It was golf ball sized. I'll never know how I didn't see it till she flipped him over and showed me. There it was plain as day. I was shocked. Well he kept losing weight so they decided the tumor was giving him failure to thrive and removal was necessary. Well the first surgery the doctors all heard his murmur which my doc thought was no big deal and would go away by one. Well the anesthesiologist disagreed and refused to do the surgery before an echo. Well after the echo they discovered FOUR heart defects. They decided inspite of his unseen heart troubles up to that moment they decided that tumor removal was necessary. So three surgeries later it was gone finally. Then at 8 months of age he had his open heart surgery. They discovered he had actually 5 heart defects. All was well and we hoped for a turn around. He was 8 months by then.
Well anyways he got failure to thrive from about 2 months off and we watched him fall straight off the charts and keep falling. I was nursing which they said was best and we upped my fat intake and eventually they wanted him to be on a high concentration of alimentum formula in addition to breast milk. Didn't work. He got hospitalized again when he was around one with the failure to thrive and they suspected he had CF. He didn't.
Anyways with all my sons problems there really wasn't that many options. I got packets of stuff from enfamil they wanted me to add to my breast milk to bulk it up. They decided that the formula was better than the breast milk but I disagreed and did strictly breast feed still. I saw no gain with the formula and he didn't want it in the first place. Couldn't have him not eating so we just did all we could with the breast milk. He didn't actually start improving till mere months ago and he's nearly 3. Not much you can do for a 3 month old. All I was really told was breast milk that was basically bulked up or a formula like alimentum that was bulked up by putting in more scoops than is normally called for in the formula was the best bet. I tried both without much for results. Basically till his underlying conditions improved he just didn't improve.
I know failure to thrive happens for no reason sometimes but all three of the children I know who got it all had an underlying medical condition and it didn't turn around till it was addressed. I'm really sorry your friend is going through this. I know how horrid it is. I know how bad and scared she feels. I'd really suggest going to a nutritionist. That was where I got the best suggestions. Not shocking really but I feel without their help my son wouldn't be in the 5th percentile even that he is currently in.