I have two pet Indian tortoises. one of them cant move its hind legs anymore. i dont know wats wrong with it.?

a few days ago i gave them a bath. they dont like water so seldom bath them. but that day the weather was cold. then today i found one of them couldnt move their hind legs anymore. i was afraid it wil be paralyzed. is it rheumatism? wat went wrong? plz help me. it cant walk normally now.