Your cat could have a disease, such as epilepsy, that is causing the seizures. It could also have some kind of brain tumor which is causing them. The cat really should be seen by a vet.
Your cat may have diabetes, the low blood sugar can cause them to go into a trance or seizure. It may also be from lack of food or water. you should take it to a vet for a checkup.
There are so many issues that could cause this- epilepsy, mini-strokes, onset of kidney disease, injury, sensitivity to medication- you really need to see a vet for a CT scan.
Your cat is in abnormal conditions because of drowning or it may be sick because of its
weakness is an one reason. Another is an it may be infected or it feel sick.