Hi Annie, it really could be all sorts of things yet I'd say the only way to rule some of them out is to go back to your gp. I am also a frequent visitor and dread having to pop back and forwards yet if you're not right you need to get checked out. Esp as we all know that anything nasty is always best caught early.
Personally I find Drs like stats. So keep a diary eg on your mobile of what you are eating/ doing when you feel the pain. So you can compare with times that you don't. Even score the pain out of ten. What makes it worse? When does it seem to happen most. It could be IBS, Coeliac, acid, a bug, a stomach ulcer, an intolerance to certain foods. Yet only the Dr can really help you investigate and rule certain things out. Do bear in mind that coeliac can show up in bloods or endos later on in life. It's worth asking your gp to check via a blood test: B12, iron, ferritin , tsh (thyroid) and the ttg and enzyme test for CD. You could even ask for the IGg (I will check this when I'm back in) as some people have false negatives. With your family history it might be best to consider a biopsy endo in future. Yet do the small steps first.
Feel free to see if anyone here has the same symptoms and do see if the medicine the Dr gave you makes any difference. My mum had similar symptoms and only discovered she had pernicious anemia and odd gut hormones as I pushed her gastro dr to check further and rule out CD via biopsy.
Good luck. Keep us updated.