When i masturebate just befor the sperm comes out it starts to pain?

near the end of masturbating just befor the sperm comes out it hurts i am 13 and i start to cry it hurts to much and will i get sick if i make sperm and my hand like my on sperm and i shove it in my but and play with that a couple time well it make me sick or anything i aint going to do just wondering