I've seen it a thousand times in multiple classrooms and schools I've worked in over the years. A young child who is typically well behaved and mild mannered starts acting out (in all sorts of ways) for evidently no reason. You ask the parents if there are any changes at home. They both say no. The strange behavior continues, so you ask again. Mom and Dad again assure you that there is absolutely nothing out of the ordinary going on and they, themselves, don't understand what is going on with their child. After the behavior continues to be askew, you press the parents one more time to see if anything, anything at all, is out of the ordinary.
And then they come clean.
"Well, we moved him into his own bedroom" or "We are weaning him from the binkie" or "His pet fish went the way of the commode" or "Actually, we are in the process of getting divorced. Mom (or Dad) moved out of the house 3 weeks ago". (You'd be amazed how many parents actually think this is no major influence in their child's life and are clueless to the fact that it does cause stress on their 1 or 2 year old. I understand not wanting to share your personal tragedies, but there are some things teachers need to know.; Not all the gory details, please. Just the bare minimum will do.)
Voila!! THANK YOU!! In that instant, I know exactly how to best help your child. (p.s. I'm not judging you or your current situation, I just really love your child and want to help them in anyway that I can)
BUT. What am I supposed to do when it's my child that is acting out all of the sudden, and I honestly have no clue as to why his behavior is changing?!? No bedroom changes here, the binkie has been gone for a couple of years now and Mom and Dad are as happy as can be.
Luckily, I think we're on the tail end of the behavior swing. I still am unsure as to what set him off. But it's breaking my heart knowing there is a reason behind it, and not knowing how to help him. If only toddlers were capable of telling us how they really felt. All the time.