Reflux? Pls help :/

I’m a FTM & my son will not sleep laying down on his back. He has to be propped up, usually I’ll rock him until he’s drowsy enough, and then then place him in his crib but he wakes right up again. I’ve also tried putting him in when he just falls asleep or even after about 20 mins of him being asleep and he wakes right up. He sleeps so well in his chair which is kinda on a incline. When he was born he would scream after eating, I figured it was gas/lactose issues (both me and his father were on specialty formula because we were both intolerant to lactose.) so he’s on Alimentum right now and it calmed down a lot but pretty much everyday after every regular feed (not a small snack, like 6 OZ) he’ll be upset, I’ll burp him and he’ll burp but shortly after he’ll spit up almost curdled looking milk. Is this acid reflux? What do I do? I’m so exhausted, I am uncomfortable leaving him to sleep in his inclined chair at night cause it’s not safe but it takes me hours to get him to sleep flat on his back and when he is he won’t stay asleep.

Thanks in advance ladies 😊