thoroughbred acting abnormal

a little background info…

I have owned my 6&1/2 year old OTTB, Messi, for just over 2 years. Upon purchasing him he was in recovery from a rear suspensory injury. He has been fully healed for about a year and a half now. In prep of the 2014 eventing season I took him XC schooling for the first time since his injury. Unfortunately he, being young and green, pulled some shenanigans resulting in the breaking of my wrist. Now, fully recovered from both of our injuries, I have been trying to get him back to full work.

this is where the abnormal behavior come in…
Since bringing him back to work, Messi has been full of energy(??) to the point that I have to lunge him for at least 15 minutes before even thinking about safely getting on. Full of bucks he has also been carrying his neck noticeably different. My boy who used to love to take contact and fill up your hands now run with his head up and his neck cocked slightly to the side, (which side depends on what we are doing).
Thinking it was something with the muscles in his neck I had the massage therapist at our barn try and take a look. Not sure if it was from pain or pure fiestyness, he managed to bite her and attempted to kick her twice. My trainer suggests seeing either the vet or chiropractor as our next step in figuring out why my boy hasn’t been himself.

Anyone have any suggestions?
Anything helps!

Have the vet check for Lyme disease.

If you have a chiropractor you trust you would have akready asked him.

We don’t have Lyme Disease here. I hope he doesn’t have that. :frowning:

How long since his teeth were floated? Saddle fit?

I vote for having the Vet out.