I dont know what to do either. I have an 11 month old girl who has been doing this daily for almost a month. When she is sick of doing something (in high chair, in car seat, in grocery car, in stroller) she puffs her chest out, holds her breath and sometimes holds her hands up in the air. I thought it was her saying "I hate being in arm restraints". So I stopped restraining her in the high chair and stroller but of course have to buckle her up in the car seat. She will sometimes hold her breath the whole car trip! Feeding her is a pain because she holds her breath, but I can still get her to eat some food thankfullly. I dont understand. I had a happy, healthy easy going baby and now she holds her breath!!!???!!! I've tried everything from feeding her on my lap, lowering the high chair, taking out the tray, putting her in a real chair, putting her on the floor, turning the TV on, radio, playing with toys in front of her, distracting her, not paying attention to...etc, etc...I've tried everything.But still, 9 out of 10 timesI feed her, she holds her breath real tight and arches her back, puffs her chest out. I read the comments and will try the water bottle thing and take her to her doctor. I hope she outgrows it and its not serious.