Suggest Treatment For Discomfort In Stomach After Food

To Doctor, I really need some help for my daughter Robyn, she is 3 in December and has always had discomfort in her chest or stomach (i cant ask her exactly as she cant talk properly yet). I noticed when she was a baby she always had a lot of trapped wind after drinking milk, more than my 1st child. She would not sleep laying down in the moses basket and would only fall asleep in a slightly sitting up position in her car seat. I didnt think at that point there was a medical problem, i thought she had colic. As she s got older, she burps a lot after eating or drinking, some times she dosen t burp at all and her tummy is very large and feels rock hard. From when she started to get around and walk (around age 1) she will lay on her back on the floor, sofa, bed or pushchair and will arch her back up and down like she is trying to get her chest to touch the ceiling then back down again, at the same time she will often tightly grip a pillow, teddy or blanket and push this into her chest/lower rib cage. She will do this at least once a day, but usually its more than just once. she wakes up in the night to do it aswell. she dosnt cry or talk while shes doing that, it seems like shes putting all of her effort into it. Ive taken her to the doctor, but shes never done what i describe in front of him. I was told she was lactose intolerant, so i changed her diet to soya milk and no dairy. there was no change after 3months. I took her back and she was referred to see a pediatrician, he said he thought she had GERD so prescribed Omeprazole 10mg along with infant gaviscon and advised me to change her diet (cut out fatty foods and tomatoes, oranges ect..) after a year there has been no change. I asked for a scan to be done, so she had a barium meal test, this came back as normal. i asked for blood tests aswell, the hospital took blood and i received a letter saying every thing was normal... she has now been signed off from seeing the pediatrician and i feel the whole process has not helped her. I know there is a problem and i dont know where to go from here, its very upsetting to see her go through this and i dont know what to do to help her. i dont feed her acidic foods or drinks, she dosent have drinks at meal times (as not to flood her digestive system) ive raised the top end of her bed by 2inches. She sometimes wont eat her dinner now as she knows its going to cause her discomfort... Please can you advise me where do i go from here? Regards, Jade laing (mother)