? Reflux

Hello,

My boy is almost four weeks, he doesn’t spit up a crazy amount and is gaining weight, but every time I lay him flat in his bassinet he spits up and chokes on it then screams in pain for a couple minute (red in the face body arched and rigid). And it takes a while to calm him down. The only thing that calms him down after these episodes is nursing but then he acts like he is in pain when he starts getting milk. Does this sound like reflux or anyone else babes do this? What has helped your little one?