Orgasm- abrupt stop or sweet release?

I am not sure if what I’ve experience is an orgasm. When I am approaching a climax the sensation is a combination of feeling really good and being painful. The sensation grows so big until it just stops. It’s not so much of a release as an overwhelming feeling of pleasure and pain and then gets shut down because it’s just too much. I feel out of control and convulsive which seems like it’s an orgasm but- is it supposed to feel like a sweet release instead of the abrupt stop of an overwhelming feeling of pleasure/pain?