My 13 month old son was sleeping mostly through the night. We did the CIO method about a month ago and since then he would either sleep through the night or get up once. When he did get up, we would just go in and tell him it was still bedtime and he would lay right back down and go back to sleep. This week he suddenly changed and will not even lay down in his crib. One night he stood crying in his crib for 2.5 hours before I gave in and got him. He almost acts afraid and screams whenever you even get close to the crib. I don't understand what happened or changed. Our routine has stayed the same, he has not had any new foods, etc. Any advise???