Very confused orgasm, what happened?

Hey guys I’m a beginner, never ever done any kind of anal play. I seriously started practicing two weeks ago consistently, yesterday I thought I’d have a session after not cumming for 3 days, didn’t expect anything to happen. Just thought I’d refine and revise the sensations and I felt from my last session. It feels good for about 2 hours after a while I thought I’d switch my position where I lay on my stomach, shortly after things started tensing up and my breathing turned into fast short breaths. I couldn’t feel the aneros in me, but I held a medium strength contractions.It builds up more and more to the point where my heart beats so hard and fast as if the devil himself bangs on the door from my inside and until everything eventually spills over like a cup full of honey that looks like a spoonful of honey from the anime, Ponyo. The dry orgasm itself only lasted for 3 seconds, and it was a pure bliss of my entire body. I laid on my back again and twisted my nipples, although not an orgasm the buildup pleasure was so strong, my entire body and head was buzzing like crazy and I saw light flashes from the corner of my eyes and I was breathing like I was hyperventilating. I couldn’t exactly pin point whether that was an anal orgasm or a prostate orgasm. I doubt it was a super since it was so short plus I’m also a beginner.