What a horrendous GP! I would immediately put in a complaint to NHS (http://www.nhs.uk/chq/pages/1084.aspx?categoryid=68), and ask for their help in getting an an emergency appointment with a specialist, (gynecologist or other). Also, I'd assume that you're seen at a surgery with more than one GP. Ask to see a different one. These are serious concerns and you shouldn't have to convince a dr. of that. I think there is some precedence in not sending a virgin for a transvaginal scan, but do ask why, and to be allowed to assess any risks/discomforts/whatever yourself and make that decision for yourself. It sounds like a lot of BS to me.
I hope you are getting the attention you need and deserve.