Horse keeps biting himself

This is my first post guys so here goes.

I've got a 7yr old gelding that bites at his shoulders all the time. None of the other horses he is with do this. I spray him with fly spray and doctor his bites with antibiotic, but he still does it. I've even seen him do it when there was no fly on him. Flies were bad earlier in the year, but as dry as it has been they really aren't bad at all. The fly spray seems to work ok, but I just can't get him to quit this behavior. He also will kick at flies on his belly with his back feet and this too has caused bare spots. It breaks my heart because he's got a chance at a beautiful coat if he would just quit biting. Any advice you can give is greatly appreciated. Thanks.

Have you talked to your vet about his behaiver?, sounds like a bordem problem, some horses either sway or crib if they are bord, doesn he do this when he is turned out too? Anther thing is to take a look at what he is being feed, some horses will have a strange reaction to there feed's

I had read that this can be associated with boredom or stress, but he is only in a stall for about 30 minutes per day and spends the majority of his downtime with six other horses who do not show these syptoms. He did spend 4 months in Tennessee this summer and his brand of feed was changed during this time, but his condition has been consistent regardless of the brand of feed or hay that was fed to him both in Alabama and Tennessee.

Thanks for any advice you can provide.

I have never seen a horse do this, I would think it was psychological in nature. Have you thought of putting a grazing muzzle on him? This might help break the habit. The only other thing I can think of is some sort of skin condition that is causing him to bite at himself. Have you talked to a vet about it?

No I haven't talked to the vet yet, but he is on my list. I plan on talking with the farrier as she is VERY knowledgable on horses, but I wanted to give you guys a chance to throw some info at me if you had experienced it. Thanks for your input.