I feel a sharp pain for a sec randomly at the bottom tip of my left testis or along with left low abdomen . i have masturbated few hrs ago and later i felt this sudden pain which i don't feel continuously. is this pain because of my weakness?

It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. However, what you described is not a cause for concern. Mastubration is not harmful to one's health. Wish you good health!

Sounds like pain from your epididymis. It is not related to your masturbation. Wear a support underwear and use local heat for a few days. However if the pain is severe you need to see a Urologist rightaway.