Perfect sleeper turns horrible sleeper

My DS is 20mths and has been the perfect sleeper since 7 weeks old but for the last two months he's gone from perfect to horrible!

We've always had the same routine and in bed by 7pm. He used to go to bed awake and then we wouldn't hear from him till morning. These days, he cries when I put him in his cot. He insists on coming out and sleeping on the couch! We do this and he goes instantly to sleep and then about 30 minutes later we put him back to bed and that's usually it (80% of the time).

We've tried the CIO method but he screams and gets himself worked up so much that we actually begin to worry about him. He shakes, gets all sweaty and just sobs his heart out.

The only thing we can think of that has changed is that he is no longer in a cot at daycare, and now in a bed. So perhaps he doesn't like the locked in feeling. I'm reluctant to try a bed though as I know he'll get up, bang on the door and we'll have to go and see to him just as we do now..

Any suggestions or advice welcome on how to get our angel sleeper back!!!

I'd try the bed, especially as your instinct is that it's the root cause.

Then, if he still has problems, I would try sitting with him in his bed, instead of the couch, and slowly phase him off that.

I'd try the bed too. A month ago dd was co sleeping (so 19 months) then DP decided he'd had enough so we started off with a week maybe .5m away from the bed in her toddler bed/cot then another week but maybe 1.5m away from our bed. The it was straight into her room. No issues at all! She even takes herself to bed now!

That's awesome to hear, well done! Isn't it funny how we always doubt ourselves when usually we do have the right answer, we're just not always confident enough to use it