What, exactly, is wrong with Lysa?

[ambi76]

I think its Cat says that she smells sickly and doesn't look well maybe she was suffering from physical illness as well.

I think I read it theorized that Lysa maybe had a Westerosi form of syphilis. Could have gotten it from her husband (going to prostitutes on the side). Another possibilty I thought of is that Littlefinger wasn't just slowly poisoning Sweetrobin but maybe Lysa as well, he sure seems to be all about poison with his schemes.