gassy and spit up

LO is 6wo and exclusively breastfed. The past week or so he is extremely gassy. He always seems to have gas pain. We have been giving him gripe water which helps most of the time, but I feel like if I have to give it to him after each feed then that's a problem. He also has been throwing up/spitting up after each feed. Is he eating too fast? Getting too much air? Am I eating something I shouldn't? 
He uses a shield not and gets BM by bottle 1x a day. I am trying to wean him off the shield. But regardless of feeding method he is still spitting up and gassy.