I am taking megalis 20 on my doctors advice from 2 years.I take 1 or sometime 2 tablets in a week.but from last 2,3 months I suffer severe headache in different parts of head and pain in one leg or one arm for whole day even it extends up to 3 days.I can't concentrated on my work.pain is not in the both legs and arms but in one leg below the knee or in one arm mostly left one.how can I overcome this pain ???