DD had it bad! At 6 weeks, fell off centiles and lost her voice. Took her to A&E because she was wheezing and threw up both boobs in immediate succession.
They weren't that great, told me to top up but DP asked them what the clinical reasoning for this was which shut them up pronto.
It tends to run in families. The valve doesn't form so food free flows back up making them vomit anything from a lot to the whole feed, so then they are hungry again.
Not so bad in bottle fed baby, buy infant gavison over counter which thickens milk but expect constipation with it. We breast fed so hated the stuff. Your GP can prescribe this, but nothing else.
Anyway DD was seen by in hosp that day by Peadatrician who prescribed Domperidon and Ranitadene which worked immediately taking the acid burn away which had made her loose her voice. from then on, a diff baby, no more screaming. She began to gain weight but still threw up some of every feed including solids until the day she got up and walked 13 months.
Its not a problem but needs to be diagonosed by hosp docs so you need a referall from GP.
there are other meds available, I think it depends on the consultant.
Do a search on mumsnet talk for reflux - you will find loads of threads and support groups to learn all about it.
Good luck