Spasms 4 weeks old

Ftm. I feel gutted and weirded out i don’t know if it’s spasms. After I breastfed my baby and he fell asleep—he was suddenly moving a lot (I thought he had woken up but usually he cries when he does) then shuts down, his eyes were rolled back or looking up with his mouth open. It happened in clusters (3 times in my case, I thought he was just straining to poop). After the 3rd time, he was sleeping normally. I didn’t took a video because I was too occupied watching him. Anyone else had the same experience?