I have a 10 year old tb gelding who has been in a similar situation . After 3 months of owning him , behavior changed ,girthy and grouchy when being groomed. We treated for ulcers by feeding egusin slh , calmed down. We had some concern about hind legs after 9 months, hocks were injected and...
My tb gelding has exactly the same issue and is prone to ulcers - this article explains that right hind lameness can be a symptom of ulcers
http://www.tcmequine.com/EGUS.html