Very strange physical tension

For the first time in my life, I recently become quite conscious of a physical tension in my body...though I think it may have been there for a long time. I'll be watching out for it from now on, but I just wanted to write as much down as I can now...and maybe get a few thoughts on it.

It is not unlike the butterflies in the tummy feeling one gets when one is scared/excited...but it is right in my groin(I'm a male BTW). I can't describe it really as sexual, as it's not quite like getting aroused or anything like that...and I never feel the need to release the tension in a sexual way.

Anyway, it seems to happen when I'm nervous...or possibly vice versa..the sensation make me nervous....I'm not sure yet. The thing I really annoys me though is that I feel this quite a often, and i think it affects the way I relate to people. I mean, I often feel/look uncomfortable when talking to people...because I am! People construe this as either arrogance, shyness and even sometimes rudeness.

I think it happens in the presence of both men and women, though I reckon it happens more with men. I have always thought of this as some kind of inferiority complex or sensation....but now that I'd really identified where it hits me physically so to speak I just don't know; I'm as sure as anyone else of my heterosexuality, so this whole thing does not make much sense to me.

I can't believe I'm the only person in the world to experience this...but I can't find anything on the subject on the net.

Can anyone give any pointers or comments? Help needed to improve my life!