Hang in there keep posting
In that situation, I would firstly if you have a bouncy chair sit him in there, put cartoons on the tv or via youtube and let him sit for half an hour
Get yourself a bowl of cereal/cup of sweet tea/biscuit sit next to him but you don't need to hold him he knows you're there
calmly (I know sorry) talk to him about the cartoon etc etc
Give yourself a break you are doing all you can - take a half hour break, let him settle with a distraction such as cartoons etc
If you have a dummy, give it to him while he's distracted
If you can express some milk into a bottle and just pass it to him while he's distracted he will naturally lift it to his mouth and figure out that he has to suck it to get the milk out
Keep near to him not out of sight and chat about the cartoon
The distraction is key to getting his screaming to stop
then everything else can be tried
Once settled with a dummy or bottle hopefully you can lay beside him on blankets cushions cartoons still on tv quietly and lift him out of the bouncer once he has possibly hopefully dozed off in there - or leave him there to sleep - up to you
Really want to help you OP