Hun i really feel for you. It is a very upsetting picture
I kinda know how you feel, Sam is a very sicky baby (never a reflux baby) but he gets bugs very easy and it takes him ages to get over it. He does those kinds of vomts daily when hes ill. Its very worrying. Luckily he now seems ok and is finally putting weight on.
Obviously the hospital have said shes fine but your her mum and if you think theres something wrong then keep at the doctors.
Go back to your gp and ask to be referred somewhere else (not sure if they will refer you to a different hospital)
Not sure what else to suggest. Is she still on any medication for the reflux? Maybe ask for her medication to be looked at again.
xx