Ok Waldo, i'll be straight with you because you sound extremely like myself.
Going by what you've said, you are exactly like me. Pre-finasteride you could have told me i had an hour to live, i still would have been able to get rock hard with a girl in front of me. Even if i TRIED to supress my sexual urges, they were too strong. Nothing mind related could ever change that. I couldn't even imagine having sexual problems, that's how sexually charged i was.
I've gone through breakups, had relatives die and all sorts of stuff. Never has my sexual function as much as fluctuated. Not until finasteride.
I've been struggling for a year by the way. I stopped it on 17th March 2010 after noticing for sure that my erections weren't the same. I figured this would fix itself pretty quickly when i stopped, but no.
Things got worse for me man. Watery semen, prostrate pains and all this sh*t developed after i stopped. It was a downward spiral for the next 9 months. Now things have levelled off. We'll see what the future holds.
You may be in the early stages, maybe not. You NEED to get bloods taken. THat would give you a vital clue what has happened if you continue to move South.
Don't panic, though. You're armed with information myself or Enden didn't have.
Chris on here was a similar case to you. He even had the shooting pains in penis and girth loss that i have had. He said he recovered after many a few weeks of intensive exercise. So there you go, you can follow suit man.
Keep us updated.
Don't stress out, stay calm and do the right things.