9 month old suddenly hates to sleep

I am at my wits end. As I write this, I've been trying for the past two hours to get my 9 month old son to take his nap.

This has been going on for about a week now. He's fine as lone as I'm holding him or he's laying near me with his bottle. But if he drifts off and I put him in his bed. He'll roll over quickly and instantly start crying. I've tried the "cry it out" method with him... but it doesn't seem to be working. After 5 mins, he's still screaming. 10 mins, screaming and coughing. 15 mins. Screaming, fumbling around his crib and coughing. 20 mins, still screaming and gaging.. you get the idea. I give up around 35 mins when he starts gaging so bad, I can't stand to listen to it. As soon as I pick him up, he'll stop crying and start cooing with his head on my shoulder.

Where do I go from here? Am I doing something wrong? He is teething with his fourth tooth but it's never been this bad.

Please help!

If he takes more than one nap a day normally then he might just be ready to only do 1 nap

My son is 15 months old & still hates to sleep  

I've been past my wits end for quite a while lol