Is what comes out after urinating and istinja' of a clear, viscous fluid—unaccompanied by lust or smell—considered madhiy (pre-seminal fluid) or discharge? And does it affect the validity of fasting?

The treatment for obsessive thoughts is to ignore them. As for the discharges from a woman's vagina: if they are madhy (pre-seminal fluid) or wady (thick white discharge after urination), they are impure (najis) and necessitate ablution (wudu') and washing the body and clothes they have touched. If they are from the vaginal moisture, they are pure (tahir) but nullify ablution. Fasting is not affected by any of these discharges.