Gaviscon advance works a treat, also an old fashioned remedy called magnesium triscilcate (tons cheaper than gaviscon)
I am a major sufferer whilst SSing, there are 2 main things, one is that normal food pushes down stomache acid, and we dont have solid food to push it down, the other thing are ingredients in the packs and bars. You may find some bars make this worse, I couldnt stomache choc orange as it really hurt, also some soups can upset me, see when its worse and if you can link it to certain flavours x