dilantin wont stay normal

i have grand mal seizures and i take 400mg dilantin a day. i have been seizure free for 2yrs. i had my seizure after my crainotomy 2yrs ago, non after. then on thanksgivind morning i had one and had a wreck. i do get warning signs befoer but i got the warning to late. i took my meds every day. i had bloodwork done and was told dilantin was to low. they give me dilantin threw iv and sent me home. i have had bloodwork done 2 times after and still on low side. my doc says im to stressed out. on christmas eve i felt so sick and i got really dizzy and passed out ,when i came to i was so swetty i had to dry off,my hair was wet.is this a new type of seizure? i went to my doc she tells me she dont understand what is going on to wait till i see a new neuro next month. this is worring me now. any ideas on whais going on with me?