Whenever i hold stool in for a long period, shit gets weird

Whenever I hold my own stool in for a while, my body begins to try and force it out, when I resist, it feels fantastic. My body almost freezes up, and I think it presses against my prostate. I'll hold it in for a few days, and when I get the feeling of it being pushed out, I clench my ass hard and try and pull the stool back in, and even get off from the feeling of it.
Also, whenever I see or hear other people when im doing this, I get really unconfortable. Like I cannot do this infront of others.

Does anyone else do this or am I beyond saving lol