Thanks everyone.

I've been working in the garden today - using power tools, lifting timber and iron frames, big pots of dirt... no problems at all. Whilst trying to undress, reaching behind to undo bra straps as I always do, it hurts. It's my arm that hurts, not the shoulder or elbow joints, which is what makes me think it's muscular.

Ho hum... I'll keep your suggestions in mind. Thanks again.

LTS