Does Taking Dilantin Cause Itchy Rash On Forearms, Thighs And Hands?

I HAVE BEEN ON DILANTIN FOR 15 YEARS OR MORE. WITHIN THE PAST WEEK I HAVE DEVELOPED A RED, ITCHY RASH. IT IS ON MY FOREARMS, INNER THIGHS, TOP OF THIGHS, HANDS AND NECK. THERE HAS BEEN NO CHANGE IN ANY DETERGENT OR SOAPS. I STARTED TAKING MORE VITAMINS A COUPLE OF MONTHS AGO SUCH AS B COMPLEX, CALCIUM, AND L-CARNITINE. MY DILANTIN LEVELS WERE CHECKED LAST WEEK AND THEY WERE GOOD, 12.

COULD THIS POSSIBLY BE FROM MY DILANTIN AND HOW WILL I KNOW FOR SURE?