Hi there. Sorry you didn't get any replies yet.
Sounds like typical 18 month regression to me
I'm hoping you guys will tell me this is a phase and he will grow out of it....
So - yes it is a phase and he will grow out of it
The 18 month regression is hard for many. The usual advice is to hang on to your routine and ride it out, offer additional comfort and resettle when necessary, not to worry too much about bad habits (although personally I would not be offering milk at 5am) but I found with mine, and often have seen on threads, that they end up needing a later nap and a shorter night after they come out of the 18 month regression, so you could try that and see if it helps - but bare in mind pretty much nothing looks like it helps through this regression.
I think the regression is a combo of developmental leap, language leap, lower sleep needs, the half birthday disequilibrium, awful teething and with all that a good dose of SA.
From what I remember things settled down again and then there was another big language leap at 21months which disturbed sleep for about a week.
The good thing about having an independent sleeper is that they often go back to self soothing as soon as they can and will little encouragement. So if you do end up sleeping in his room on the bad nights I wouldn't worry too much about it.
hope this helps