Is it legally obligatory to avoid doubtful matters, and what is the ruling concerning the obsessive person who views everything as doubtful, forbidden, or impure? Is it obligatory to adopt a precautionary approach and the stricter opinion in cases of jurisprudential disagreement?

It is clear that obsessive whispering (waswas) has taken hold of you. We advise you to turn away from it and not pay it any mind. A Muslim is not obligated to adopt the strictest or most rigorous of opinions. If a person is afflicted by waswas, there is no harm in them taking the most lenient of scholarly opinions to alleviate hardship and remove difficulty.