Thanks for the replies so far! I can also play classical guitar so I know about sitting position etc. I'm right handed and it's my right arm that is the problem. I play my steel string with the strap at the end of the neck, not attached to the body....it's a girl thing (we have breasts you know); it seems to fit my body better. My steel string guitar is a Rokkomann, it's gorgeous but it is big and I'm small. I often play it sitting in the classical position but that is hurting my elbow, so I am going to try playing standing more than sitting.
Cheers
JennieG