Nap suggestions?

My almost 4 month old will not take a nap anymore. He gets to the point of screaming for hours because he is so tired but he will not go to sleep. We used to have a good routine where an hour and a half after waking up we’d get quiet and still and rock or take a bath or do massage or baby yoga and he’d go right to sleep at the two hour mark. Now he fights it to the death. I’ve tried nursing him to sleep but he overeats and spits up as soon as he falls asleep. I’ve tried reading and rocking and white noise. He’s too little to cry it out. The only thing that works is putting him in his car seat and swinging it or riding in the car but that’s not sustainable. Any advice? I’ve tried EVERYTHING, he just won’t sleep.