Strangles in horses: i have a gelding that seems to have strangles but not all of the syptoms ?

He has absess between his jaw bones. He has ran a fever. But no pussy drainage from his nose and he has not pulled off his feed. Should I give him penicillin or should I just let this run its course. He has had an absess for about 2 1/2 weeks. I have heard that if you give them penicillin this far into the infection that it could cause it to go into bastard strangles.