Help! Son is refusing bottle.

I am having a lot of difficulty getting my 3 month old son to drink his bottle. He has reflux is generally colicky, and about a month ago he started refusing his bottle. He went from drinking 4 oz at a feeding to 3oz, and it is a fight to get him to drink that much. He generally drinks the first ounce fine but then starts screaming and turning his head from side to side. We have to take a lot of breaks and I have to stand and walk around with him to get him to eat. He is on Zantac for his reflux and is on nutramigen formula but nothing has made his feedings easier. He is healthy and does continue to gain weight but I am worried that if he continues to eat this little he will start to lose weight. I was also hoping that by 3 months he would be sleeping better at night but from all the research I have done I find most people recommend getting your child to eat more during the day so they sleep better at night, but of course since he refuses to most times even finish 3 oz i can't imagine trying to get him to eat 1 to 2 more oz per feeding so he sleeps better. Has anyone else out there experienced this with their infant and  I would really appreciate any advice someone might have to give as to how to get my son to take his bottles more easily.