Tahaarat

Doubting the Cleanliness of One's Slippers

Q: My dad has a pair of relatively old brown leather slippers. As I am not an expert, I do not know if any part of the slippers is made from cow or pig leather. Yesterday he used those slippers for wudhu and with wet feet, he walked in a carpeted room for Salaah. I then performed wudhu in a separate pair of slippers and walked in to the same room, with wet feet, to perform Salaah in Jamaat with him. Some wetness that remained on my feet, transferred to my clothes whilst in the sitting position. My dry hands touched the same carpet. Questions are as follows:

Wudhu With Nail Polish On One's Nails

Q: As nail polish nullifies wudhu, is it okay for one with onychophagia (nail biting disorder which is part of the OCD spectrum) to wear clear nail polish or bitter tasting nail polish to prevent her or himself from biting as it is damaging to the skin around the nail, cuticles, etc and puts the person at a risk of infection if they don't take steps to stop nail biting or is it still haram despite the health risk?