Our dog has been having seizure episodes, is there anything we can do to help her?

She is a two year old border collie mix. They have been recurring late at night since mid October about every other month. When they happen she loses her balance and can’t walk, she has heavy drool, and she vomits and loses control of her bowels.

These symptoms last around twenty minutes. She has the shakes for about an hour after she regains her balance and the other symptoms pass. After about two hours she is back to acting like herself.

She’s very scared while these are happening, we’ve been comforting her until they pass. Is there anything we can do? What could be causing these?