Peeing outside the box may be seizures ?

I just observed my little kitten that has Pectus Excavatum have what looked like a partial seizure.  This is the first time I have seen this in  her.

She was at the vets yesterday for her final FVRCP and Rabies shot.  All systems checked okay.  Due to continual peeing outside the litter box, the vet checked for another bacterial infection.  The vet saw white cells and some blood and sent off the urine to a lab.  He then gave her a long term full spectrum antibiotic injection.  Her littermate also had the same thing, all this started after they went to a mass spay/neuter clinic.  Thinking that maybe things weren't very sterile there.

This morning I found her in the corner of her litter box shivering all over.  She didn't want to be touched and seemed disoriented.  I moved her in the litter box beside my computer desk and kept a hawk on her as this was not normal behavior for her. I thought maybe she was in pain due to a urinary tract infection.   Shortly after I moved her and the litter box to the new location she hopped out and did not want to be touched. Four hours later, I observed her walking around the edges of the litter box and trying out each box to find a good spot to go.  When she urinated it was alot, possibly she was holding it for those 4 hours. There was no straining when she peed. 

Then she perked up and played with her litter mate.  I heard this cry and turned around and she was having a rapid fluttering of her rib cage, her mouth was hanging open and tongue was moving and her eyes were rolling around.  It lasted for maybe 5-7 seconds.  Then it stopped suddenly, she laid down and was quiet for an hour and then got up, ate, pooped, peed more and resumed playing with her litter mate. But during whatever it is that happened, she did not urinate on my bed.  Recently there has been more pee on my bed and around the litter box. 

I am waiting to hear the results from the lab on their urine test and waiting to discuss this recent occurrence with my vet.

Thank you for listening.

Just heard back from my vets and the female with PE does not have a urinary tract infection, but her litter mate does.

In describing to my vet what happened to my kitten with PE, he said in all probability it's a seizure she had.  There is really nothing that can be done and he doesn't want to put her on any anti-seizure meds right now.

Thank you for listening.

Could be the convenia shot(I assume it was convenia) or reaction to the vaccines.  I would not vaccinate her again except for Rabies if that is a concern in your area.  Issue is the Convenia can take a long while to leave system and for a cat you can pill it is never recommended.

Yes, she received the Convenia injection   Thank you for the advise about this. I just read up about this and it can reduce the threshold for seizures. 

I feel soo bad for her now.  She's my little jewel.  Just watching her go thru this seizure was utterly devastating.