Hi V.. Well, first of all, children can change their behavior at that age quite frequently and it can be due to anything from teething to growth spurts and learning new things. They usually revert back to the original behavior or progress as they age into new schedules and behaviors. Just go with the flow. That is the best thing you can do when it comes to things like that.
Secondly, as far as getting your child to his crib, well, the only way I can suggest is to just cold turkey him. I understand your reasoning for having let him sleep with you early on, but he can't sleep with you forever. My children never slept with me, even as infants, unless they were sick. I made a vow I did not want to start that. It's been great! However, having had gone through times where our boys would not go to sleep when it was time and so forth, sometimes letting them cry is the best thing. It's not easy. My youngest used to hate to take naps and my husband would let him cry until he fell asleep and he would cry anywhere from 10 minutes to an hour. I know, seems horrible to let them cry that long, but believe it or not, they are smarter than we think. They cry b/c they know we'll give in. If we don't, they'll eventually learn. Parenting is not easy, but I am so pleased when I see the fruits of my labor coming through. We work so hard to teach our chilren properly and it can be long, frustrating processes, but eventually, they learn and prove our system to be correct.
You can try sleeping in his room (on the floor probably) while he goes to sleep in his crib for a week or so. That could help, but I don't know for sure. Just remember that it will not happen overnight. You will have to do these things more than once for sure.
Good luck! I hope I was of some help.