Re: Enhancement pills. Question about their mechanism.
RE: azza15292 "i tried Cialis for the first time last night.. "
It COULD be nerves... but do you have anything going on in your life (as a 20 year-old) that's really bothering you THAT much? The mind does play a big part in getting and sustaining an erection, but at 20, you should be getting erections just by looking at billboards...
I would ask how "turned on" are you by your girlfriend, but you mention that even when masturbating, it's not staying erect. That happens once in a while if you're head's just not in it, but it shouldn't be a regular occurrence.
If Cialis didn't work, try viagra. Try 25mg at first, then 50mg another day, then if that doesn't work, a last shot should be 75 or 100mg. If that's not working for you I would think there's something else going on. Maybe physical, but more likely, something "mental" that's really affecting your body's ability to become aroused. It's actually more common than you might think. But still, for an otherwise healthy (?) 20 year-old, not TOO common.
I hope this helps a little. I'm not a doctor!