Peter T., it sounds like the problem isn't nerves, it's playing and singing at the same time.

I have the very same problem trying to sing while playing the Doumbek. *But*, I can play the bodhran and sing at the same time.

What I figured out was that I learned the doumbek alone, and never tried to sing along with it while I was in the actual "learning" stages. I *did*, however, sing along as I learned the bodhran, and so trained the synapsis to do both along the way. I still cannot play that damned doumbek while singing. Good thing there isn't much call for it in my current band.

Might take a total retraining of the grey matter for you to do both. Again, sounds like it may not be nerves at all.