Gerd and wind

My 18 week old baby girl has gerd although zantac has taken away the pain and carobel somewhat helps the vomiting. She is only 11lb 4oz and is in the 2nd centile. She only takes 4 5oz bottles of nutramigen 1 each day and when I try to give her more she just vomits it up due to her reflux. However she has extreme flatulence at night from 11pm right through until 7am. It is constance, is foul smelling and doesnt stop with the result neither she nor I sleep.  Does she need to see a gastroenterologist. I feed her upright, move her legs ect. She burbs during every feed often several times so why does she not get any relief and why does the flatulence keep going all night, very painful for her and huge ones! I need help. She is a bright and active baby who has no other problems but I am now exhausted. Should I try her on baby rice?