I had Strongyloides of 8 years and was misdiagned by dermotologist after dermotologist. You are right, thay will not admit to a parrasite but they are very willing to call you crazy. Finally I got an APRN to run the Strongyloides blood test and my antibody count for Strongyloides was off the chart. I took the medication Ivermectin three times. I was tested a year later and the antibody count was back to normal. However, I just recently learner from my GI doctor that not all the worms are killed. there is a small fraction that go into stasis in fatty tissue and your brain waiting for the opportunity to awake.
If you demand the Strongyloides blood test from you GP it will be hard for him to say no.
By the way, my sinuses where devistated with the worms and even with the cure there is so much damage. In order to breath properly I must insert tweesers deeply into my nose and pull out the semi hard mass of blood and whatever to clear my nose. I recomend a sinus rinse by Neil Med, it loosens the masses clogging you sinuses which makes there extraction som much easier.
Remember, you must get the Strongyloides blood test. It is the only document that will give you credibility.