Read (wikipedia) that cremaster muscle can experience spasms/cramps which can b chronic& debilitating in adlt males, treatment may involve botox, true?

Botox for spasms. Botox is used for temporary relief of muscle spasms/contractions and has been used commonly in facial aesthetics to treat deep frown lines, to treat migraines and hyperhidrosis (increased sweating in armpit areas). So, it can be used for the cremaster if other treatments have been availed without success or benefit.
Not commonly. While the use of Botox is well known for helping facial dyskinesis or synkinesis following injury, its off label use for the cremaster muscle is so e what isolated and not at all common. Other than wikipedia i could only find one reference and it is not a relatively rare condition to my knowledge and urological colleagues.
Cremaster Synkinesia. Cremasteric synkinesia is a rare disorder & not very well documented as an a well defined entity in the medical literature. Pain in this region is more likely to be from from the nerves that supply the muscle and not the muscle itself.