I'm sorry you are having a hard time getting a diagnosis, and don't blame you for feeling frustrated. There are commercial labs that will do tests for parasites without a doctor's order. You can Google to see what is available.
If you have parasites in your stool, you will want a "Fecal Ova & Parasite" test. For bloodborne parasites, there are blood tests. I am not sure what specific tests are available for skin & hair, as these tests are normally done by a dermatologist who uses a scraper and places the sample on a slide.
Of course, without a referral, you will probably not qualify for insurance or Medicare reimbursement, and will have to pay out of pocket for each screening.
Doers this give you a direction to pursue answers?