Oh dear i do hope you can find out the cause, i can imagine how frustrating it is for you all , and please don't let them get rid of Lexi, that would be cruel, imagine if when people get old and incontinent we just got rid of them, not quite the same but you know what i am trying to say, maybe it is stress related, i am no expert, but if you have had her medically checked,and all is ok with her, then listen to other's idea's as they really are people with all kind of experience's with kittie's,if only our furbaby's could talk and tell us why they do what they do, but they cannot so we have to realise there is always a reason for what they are doing, remember they are not malicious like human's can be, and don't do things on purpose or to be spiteful.

Btw I too have a kitty called Lexie spelt with the E, she is the black kitty in my siggy, so from one Lexie to another,please don't get rid of her,there really is room for two of us on PT,she is indeed a very pretty kitty .