Dogs and seizures, can they just start after years of nothing?

my boxer, almost 6 years, the last few days has had only what i can describe as a seizure.lasting less than 2 mins, and over at least an 8 hour apart gap, she has had about 4 of them. Now all clear for almost 15 hours, and from the beginning she has been everything all hunkey dorey until, BOOM and it just happens. any ideas, vet says has to try several tests, and and arm and leg later, idk they cant be sure??? she was bit a few nights ago in the yard, but was treated with benadryl at her dose per the vet. she was ok within half hour. shes full AKC, champ bloodline, family tree, etc... doesnt get in nothing, PERIOD!!! stool is normal, no vomiting, etc... and shes eating and drinking, walking, running, everything as normal as always. any suggestions would help ? ? ?