Can you give us a few more clues??? Lame on circle, lame in hand or just when ridden, which leg(s) lame on, how bad lame on a scale of 1 to 10 - 10 being worse, is he shod, when was he last shod, why does he get abcesses, etc, etc. As he is a TB he may be more prone to brusing as they tend to have very flat soles, also they are often low heeled and long toed which doesn't help. It could also be a corn, and his foot confirmation could be a reason why he gets abcesses.
You will have to be a bit more specific. If he is very lame get the vet, if he is only 1 or 2 tenths lame box rest, leave off work for a few days, cut out hard feed, give ad lib hay soaked if necessary and sit it out. xx