overly playful

Question
hello kimberly!  first of all, let me thank you for volunteering your time to help others.  its not often individuals will help without some kind of profits.  so... thank you.
ive been around horses, and usually dont have any kind of problems with them.  but today, my 3 year old colt paint is acting quite different.  going after the dogs, going after me, not overly aggressive, but more in an overyly playful tone.  i sat down and tried to talk with him, to find out what was wrong, but he still hasnt said anything to me!!!  haha.  he tries to nuzzle me, but then tries to nibble at me, no, not hard, but like in a well... overly playful tone.  i didnt know if hes trying to tell me something, or just in a good mood.  didnt know if hes trying to come down with some sickness or what.  but today is the first time hes ever acted like that.  none of my horses have ever acted like that.  if you could, please let me know what you think.  
thank you,
darren rapp

Answer
Darren
Sorry, my first answer somehow didnt get to you. I think your horse is acting out of aggression and play at the same time, but it should be handled as aggression since play is dangerous to a human.You have to stop this behavior befire it gets dangerous and he learnes it is okay to demonstrate this behavior. First, since this behavior came on rather quickly, have him checked by a vet to see if he is in pain or discomfort. If this is not the problem, Become more strict while handling your horse. Especially if hes a stallion, he may get nippy and heady. Dont let him act like this. When he advanced towards you in an agressive/playful manner, ward him off by comming towards him swiftly with your arms up. This will intimidate him, but if he strikes back, this situation is very serious. Your horse for some reason is untrusting and acting out agressively. Try doing join up with him. This will establish a neutral relationship with him involving trust and knowing whos boss. If I have said anything unclearly or you have further inquiries, please post another question,
Thank You
       Kimberly