At a little over 2.5 my DD (older) started telling us she did not like going to her daycare, that the kids did not understand her etc. That said, the staff have always adored her (with the possible exception of her current main caretaker) and she has always had friends there. But this is the year she stood out from the rest in obvious ways.
She is usually pretty happily playing when we pick her up, or drop by. Long story short I started checking into preschools and found that for her we think and hope a Montessori will be best, because of the 3-6 age group. She is starting there end of August & turning 3 in September. It will have its own challenges, including a big schedule change for us, but if you have a sense this is not the right place for him now, it probably isn't going to be in n months either.
Good luck and please keep us posted.