Cat Seizures

I'm trying to find out what is causing my cat's seizures. I've read up on cat seizures online. I don't think it's regular cat seizures. I think it's something he's allergic to. I took him to the vet and she did all the blood work, she can't find anything wrong.

My daughter found him, he was about 4-5 months old. She kept him about 5 months and she never saw any seizures. Then she gave him to me because she has too many animals. We've come to the conclusion that he didn't strart having them until I started using a store bought liquid flea control, the kind you put on the back of their neck....Hartz brand I think.

I noticed he was only having them about once a month. He's an indoor cat. When I went to put his flea medicine on him last month I began thinking maybe that is what was causing the seizures, so I didn't put the med. on him.....and as far as I know he hasn't had another one.....but he sleeps up under a bed in a spare room and he could have had one then....sometimes they only last a few minutes but then he sleeps for an hour or so afterwards.

Anyone think it could be the liquid flea medicine?