4 weeks today-Only sleeping in 30 min increments

Hi! My son is 4 weeks old today. He's been doing great nursing with nipple shields. Gaining weight, soiling appropriate number of diapers, no complaints there.

In the last 48 hours, he has only slept in 30 minute increments unless he's laying on my lap on the Boppy pillow. I feed him and he passes out. We move to crib or bassinet and he is up within 30 mins.

I am exhausted and dozing when I should be focusing on him because I am not getting any rest. Any idea what's up? Maybe reflux? He doesn't spit up much or cough etc.