Hi Helen,
saw this post and its interesting as i have 4 children and never experienced this til no4!
My dayghter (Nearly 6 months old) is very sicky, she is sick constantly, after every meal, between meals, over everything, herself and everyone!
She seems to burp but it come up sicky, solids have made a slight difference, she keeps solids down better than my milk!
I asked hv just yesterday who said as her weight is fine and no obvious signs and it should clear up by 12 months!
I will keep an eye on her and not worry too much as long as her weight is ok.
I was born with a weak stomach valve and other stomach problems but the stomach valve is what lets stuff back up, my dd may have the same as me and if so certain foods are worse than others to cause problems, you can only tell by trial and error what foods are tolarated and whats not.
There are also natural things to help as suggested in other post, and personally i am better when i am on a prebiotic a day which munch bunch do for kids and after 1 yr old i would think they were fine.
Sorry I am not too much help, but if nothing showed on x-ray its nothing obvious so just try some different foods and keep up with the food diary, it may be something you are not thinking of, i always thought of natural products to be better but my dd is worse on my breast milk!! And ds has a type of reaction to apples with his behaviour so anything is possible!
Good luck with it,
Pinky xx