Welcome to the board, My Gatosan.
Unfortunately, you're likely not going to get a decent diagnosis over the internet. For the most part, members here are not vets, and none of the vets would be able to venture more than a guess as to what's going on. Your cat really needs to be seen in person by a vet.
You need to know what you're dealing with before you can begin to treat it, so pls take your cat to a vet, and sooner rather than later.
I hope Gatosan is feeling better soon!