Hi MATTHEW AND WELCOME,
had my P for 12 years now,comes and goes but always there,spreading quite badly at the moment,but never mind.
Have been uses different creams etc all that time and my dr was much the same as yours,reluctant to send me to a derm.
Finally told him last monththat I wanted to see a derm as its now spreading again and that the specialists are more up to date on the latest treatments etc,and he caved in-AT LAST!
You know your body and your P if you feel you need a specialist then say so,gps dont have all the answers all the time.
And good luck x