6 week old wont sleep more than 20 minutes

So my 6 week old son has pretty bad reflux (hes on zantac for it) as well as colic. Yes, I probably sound dumb even asking for advice but somethings gotta give. He wont sleep longer than 20 minutes!! If hes in his rock n play he will but we only let him sleep in it during the day when hes supervised as it can cause sids. He has a bassinet right beside my bed i put him in once he falls asleep and he wakes right up. Can he become dependant on rocking at such a young age? Ive tried putting him down when hes drowsy but slightly awake, as well as making sure he doesnt need anything, and ive patted him back to sleep when he wakes up but none of it works. I am so tired 😪 someone help. Hes on enfamil a.r. for the reflux and i thought itd make him more full but it doesnt. I feed him til hes full before i put him down. Im just so lost here. My first baby slept. And i dont want to hear any comments about breast is best. I breastfed him but he was allergic to a protein found in my milk so I stopped.