Gassy Baby? HELP!😰

Im new to this whole parenting thing so I just need some advice, not really sure. 
So my daughter is almost 3 weeks old. 
Im starting to feel like my brestmilk upsets her tummy or something because every day, all through the night, or right after i feed her she grunts and pushes and turns red and cry and I hear her pass gas but not all the time. Her tummy bubbles and everything. Its almost like shes backed up. She also pukes often after i feed her. The Dr. gave us medicine for acid reflux but im not sure what to do about this. 🤔 im not even sure what it is! She gets very uncomfortable I can tell, and she squirms and tightens up and i feel so bad for her because im not sure what to do 😢 Its like she tries soooo hard to push and it seems like its such a strain on her! Then she starts to cry. Ive been trying Gripe Water but it dosnt work!
Im paranoid about almost everything when it comes to her 😩