Reflux?

My LO is 10 weeks today. Around 2 weeks ago he started acting fussy but I figured it was a growth spurt or something. But for the past several days he refuses to lay flat. He screams if I hold him flat, lay him down flat etc. He started spitting up multiple times in between feedings, he tends to scream when we try to feed him. Now he's started making this choking/gagging noise randomly, and he has very wet burps. No fever, and he will usually calm down if I hold him at an angle.

I'm gonna call his pediatrician in the morning no matter what. But do you guys think this sounds like reflux? Could it be something else? He had his shots last Thursday but this was starting to happen before that.

Thank you!