What Causes Erectile Dysfunction While On Focalin?
Not indicative of muscular dystrophy
Detailed Answer:
I read your question carefully and I understand your concern.
While it is natural to be worried given your family history, I do not think that those episodes are indicative of muscular dystrophy. Muscular dystrophy is a gradually progressive condition, with weakness which appears and remains present all the time, not in such acute episodes leading to falling on the ground. Would be present for many actions, not only masturbation. Also, it doesn't have sensory symptoms such as tingling.
Since you mention it to have happened after being seated one possibility would be nerve compression, of the sciatic nerve, due to the seating position. That could cause the symptoms you mentioned, usually transitory.
Another possibility is that the issue is related to your sleep disorder. Sleep disorders are at times associated with issues like sleep paralysis. However your episode involving only lower limbs doesn't fulfil all the criteria for sleep paralysis, so not that likely.
In any case, it is not related to the ED and if not associated with other symptoms is not indicative of something serious
I remain at your disposal for other questions.