Hi Dande - welcome to our community!
If your PCP won't sign off - can you go to another Dr. for a signature? A ND or Chiropractor can sign as well.
There is also another option - there is a lab called TruHealth Lab - they will send you the test kit that you can take to da lab - without involving your Dr.
But the testing does cost more.
/www.truehealthlabs.comI do have some LLMD's listed for PA - you can contact me via email and I will send you names.