I think my 3 year old male cat had a seisure. There was a rucus last night at 2:00am and I awoke to a lot of noice (could have been him, or the other 4 cats running around in the window and down the stairs). I found my nutered boy cat in a cardboard box they generally play in, and his back end was laying down not moving but his front end was more sitting up and scratching rather furiously and his nose was pushed into the corner of the box. He looked like he was going after a spider or something. I called to him and when he didn't look up at me or stop scratching, I went to pick him up and saw his tail was a little wet and I thought he ran through the water dish; but then realized it smelled like urine. His eyes looked a little glassy and he was not purring. After probably 2 minutes, he stopped the shaking, and I picked him up and he then walked away, okay. But, the other cats were smelling him like they knew something happened. He was fine this morning, running up the stairs for breakfast, and purring. The only thing out of the ordinary is we went away for the weekend Friday coming home Sunday, and left plenty of food and water, but perhaps he over ate? There was some food and water left over when we returned, but Phil did look a little larger. Do you think it was caused by over eating? We generally separate him and the others as he will eat his portion and then eat the other cat's portions if we don't separate them. Having gone away, we couldn't do this. What should I do if it happens again? i.e. do I pick him up, or leave him be?   
Thank you,
Audrey in California

Optional Information:
Age: 3; Male; Breed: Short hair

Already Tried:
First time it happened. Oh, he previously had crystals in his urine about 8 months ago...could this be connected?