I second the reflux idea. DD1 had silent reflux, I could count on two hands the amount of times she actually chucked as a baby but that arching and screaming was hell. She was finally diagnosed by her fabulous Paed (our GP was useless TBH) at about 10 weeks and put on Losec. We noticed a massive difference within days.

DD2 was also on Losec for reflux but she was a big chucker but there was lots of issues like you're describing especially when she was over hungry.

Good luck, I hope you can find a GP to help you.