Piglet, I think you are very wise in getting a medical opinion. Did you notice that in your update that he mentioned he was afraid? Fear of performance can be crippeling.
Hmmm. Maybe you need to look into something I saw elsewhere on this board as well. It dealt with scheduling times for intimacy. Not sex, but just being naked together. Time specifically set aside just to be alone together and then starting with small touches, without the pressure of having to go through the full act, working your way towards arousal together over many weeks. I don't know where to find it, but it sounds like a good route and I saw it on the board in the last week or so.
Depression can really mess with the mind and cause severley conflicting emotions and drives. A drive mismatch (I'm horny, why can't I get aroused?) is a good symptom. I'm not a doctor or someone who deals with this problem but it sounds like it would be a good thing to look into.
