just another thought amongst all the many:
I was having severe pain in my elbow on my comfort bike. When I started talking to my LBS guys and paying closer attention to my riding - I discovered I tended to "pull" on the bars whenever I was climbing or standing in the pedals. The comfort bike had seagull?? mustache?? bars - don't know what they were called but it had a slight bend in them and I was trying to either get in a more aerodynamic position or using the bars for leverage. Either way - when I stopped pulling on the bars (and switched to flat bars) the elbow pain went away.
So, are you pulling against the bars?? Plus what everyone else said - your arms and hands don't "look" comfortable to me anyway, they look very awkward and tight.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"