horse turning off his head seeing me

Question

turns off   hello. i am always thankful to you for answering my questions (which are silly and serious) with lot of patience.

this below is a serious question :

hello sir, we have a 6 year old bay thoroughbred racing geldng who always turns off his head whenever i approach him when hes in the stall, may i know why? is he frightened of me? is he frustrated of human beings? please tell me how to correct this problem.

about the horse:
he has a sleek body frame. last year he performed very well and won 3 races in 2 different seasons as a 5 year old. now he's 6 years, his performed slowly degraded. now, whenever i see him, his left side of the muzzle looks small when compared to his right. as a 5 year old, his groom was different. horse was too mean, biting and kicking. in a hurry, he did a mistake of sliding the bit in the mouth too fast which resulted in the horse tongue cut. trainer appointed a new groom who corrected the animal but the horse condition looks poor sir.

Answer
The signs you are presenting tend to lead me towards a medical problem with the horse. There could be some nerve damage with the horse's mouth or some type of atrophy (muscle weakness) in the mouth. I would suggest you have a vet come out and examine the horse. And, I would do it quickly. If the horse's condition is becoming worse, I would most definitely have a vet check him out.