Is ghusl required upon seeing small spots on one's garment resembling semen, without feeling nocturnal emission or anything exiting, especially with the possibility of madhiy (pre-seminal fluid) exiting and being felt, particularly given one's suffering from scrupulosity regarding wudu and ghusl?

Ghusl (definition) is not obligatory as long as one is certain they did not have a wet dream, especially if they are experiencing obsessive thoughts (waswas). If they predominantly think some drops were discharged, these are madhiy (pre-seminal fluid), which is impure and requires cleansing the clothes, but it does not necessitate ghusl.