My Husband Is On Dilantin Liquid Through His Feeding Tube.

My husband is on Dilantin liquid through his feeding tube. It is normally at a 15-18 level. Last week it dropped to 4 and this week it is now 25. He also takes lamictal. How do we get the levels back safely? The doctor wants to stop the Dilantin for 2 days to lower it. Are their other meds that he can take with lamictal and get off of Dilantin? Lamictal does not work alone for him.