No referral to the dermatologist made! The GP was pretty certain I had something called pityriasis rosea which can at it's worst last up to six months and they think - but don't know - that it's caused by a virus. I did have a temperature at the appointment and she's putting this down to my night sweats and aching joints and muscles.
As for the stabbing abdomen pain; I guess they've given up trying to find what that is and it's something I'll just have to put up with. Thank you all for your support though!