indigestion

I get this on certain days.. feeling full & feel like vomitting. sometimes after a meal i feel fine.. but sometimes i feel like its not digested properly & i start to burp & feel like vomitting. How do i prevent this? Im not eating alot and i do chew my food slowly. I also eat probiotics on certain days. I just dont know what is wrong & sometimes i cant sleep the entire night. I tried walking around the hse after a meal but sometimes it just doesnt work & my feet gets very tired of all the walking. I just want to rest after a long day at work ?.. gynae suggests gaviscon so ive been eating it once i feel like an indigestion coming up.. dont know if it would harm baby in a long run. What should i do? I feel tired feeling like this and i dont know how to make myself feel better... gaviscon does provide me temporary relief but i dont want to depend on meds everytime i get this. :(( feeling very lost cos i dont know what to do...