Trouble patching and sleeping

I have tried every sleep training method and trick I can find, but my 4 month old will not sleep. He’s been doing this since 2.5 months which is around the time he suddenly stopped latching. We can’t let him cry it out bc he just progressively gets worse and then starts snorting like he can’t breathe. I’m trying to figure out if the 2 are related. I’m seeing a lactation consultant next week. I’m taking something for thrush just in case (prescribed), and as of today, I’m cutting out all dairy per recommendation from a friend. He goes to the pediatrician on Friday. Every time he wakes, he screams bloody murder like he’s dying and clings to me for dear life. I’m with him all day, and he’s too young for separation anxiety. Does anyone have ANY advice?!? I’m tired.