Weird twitchy orgasmy thing??

So I started masturbating a couple months ago and it’s only clit stimulation but I’m not sure if I’m having an orgasm or what because my “nether regions” get all warm but then my body starts convulsing? I can’t really describe it but my abdomen tightens really fast and then releases like I’m the Flash doing crunches. But every time the tension just builds up and I never actually release but it’s kind of wonky.