C.,
My son is 21 months and had sleep issues all the way up until he was 13 months old. The first year children are going through so many changes, growth spurts, new teeth, etc. and these all play a part in how well the little ones sleep.
My advice is, try and calm him down where you want him to sleep. If you do not want to co-sleep, then I would stop bringing him into your bed right away. When my little guy woke us up at night I would go into his room and try rubbing his back first and if that didn't work I'd pick him up and rock him a little while humming a song or saying "shhhhh" over and over. I never turn a light on as I think that just wakes them up more.
Try putting him back in his bed awake and lay on the floor next to his crib for a few minutes. Once he is calm, leave. Each night move a little closer to the door and eventually he'll just go to sleep on his own without having to see you or touch you.
I would check to see if he is wet or dirty as my little guy hates having a dirty diaper at night. Most nights he stays dry now.
Also, fill him up before bed so that he won't wake up hungry.
Good luck and hang in there! Before you know it he'll be back to his old self again and learning some other new trick to keep you on your toes. :)