I bought clevamama sleep positioner wedge (but be careful and must stop using once baby can turn) and I think it helps a bit. Bouncer helps best as it is more upright but can’t let him lie on bouncer all the time. So lie on bouncer (or carry upright first) then on clevamama. I burped him over the shoulder but he will regurgitate a bit. Also fed him biogaia probiotics. I think now getting better as baby grows ...
Before that, he made growling noises throughout the night as he slept because he was uncomfortable lying flat...