Hello , I am getting weekness recurrently from backside lower hip and gluteus muscle and tail bone under muscle till scrotum muscle and inner ties Gracilis muscle , while sitting I am getting very soft and feel it's pressing in tailbone feel like something missing for muscle for better tone  and gastrocnemius muscle getting week and some time feel better if I took vitamin d3 and calcium tablet , so what could be the reason cause of it, its related to nerves, muscle,or vitamin d3 issue causing it ... or any ostrioporiosis issue .