Why am i experiencing this A-less, anyone have similar experiences?

I’m a new user, i’d played around a bit down there, decided i was curious enough and ordered a helix trident which i’ve had for 4 days/3 session. I did some reading, and tried to follow most instructions, Things were generally pleasurable during but did not result in anything mind blowing which was fine. Today was an off day from an aneros session, however when i was in the bath, i had this weird sensation when i flexed sphincter (as if i had the aneros in), so i kept doing it and it started to feel really good. I started to get hard, and get involuntary spasms pulsating from my prostate all the out to my full crotch, heart rate went up, minor convulsions through the body (mainly abs). This was pretty much how it felt during the aneros sessions, except maybe a little less intense this time. Anyone have any idea what’s going on? I imagine i simply was able to stimulate prostate without the aneros, does this mean i should change anything with my sessions/toy?