It is true that Dilantin can cause skin reactions or cause disorders which could cause skin symptoms, but given the fact that you have been on it for a while without symptoms makes me pause. It still may be the Dilantin, but I would have other disorders such as connective tissue or inflammatory disorders evaluated. Also Dilantin can cause your white blood cells to decline which may predispose you to infections. This can be evaluated by having a complete blood count performed.
I assume you were placed on Dilantin for seizure prophylaxis. If you have not had a seizure then you may be able to come off the Dilantin. You can discuss this with you Neurologist. Good luck.