one of our females pee's in a basket of clean laubdry if the litter box hasn't been cleaned to her liking, meaning EVERY DAY. So maybe she's trying to tell you her litter needs changed?
Other than that, is she spayed? We had a female with feline lukemia that we hesitated on spaying and she would come in while she was in heat and pee and bleed all over our beds. We finally got tired of it and risked the surgery which she did fine through.
thats my 2 cents, I hope you can figure it out, must me horrid!