I don't know what throwing a clot means... I'm thinking he has a blood clot in his leg or somewhere near his legs? Or did he have a stroke that affected his legs? I am just not sure what you are saying. Either way, I wish him and you the best.
What does the vet say?
"Be who you are and say what you feel. Because those that matter, don't mind...And those that mind....don't matter."
How do you know that it was a clot? Could it be a spider bite? or a snake bite? If it truly is a clot and you did not take it to the vet, it may be to late to treat it. So sorry for your kitty. I hope it recovers.