How do you get your doctor to believe you?

How do you collect samples of parasites? I went to an infectious disease "doctor" with samples on several pieces of lint roller tape, and he would not even look at them...said it was lint. First he said that parasites were microscopic, then he wanted me to pick the parasites up and put them in a container.??? I asked him to look at the rash on my back, he stood about 5 feet away and said it was just a rash and not parasites. Then he said "Let me play the devils advicate, what if I were to tell you the last 5 patients all had the same symptoms, but they had delusions of parasitosis." Now why would someone pay $800.00 for 10 minutes if they "thought" they had parasites? The only thing he did was draw blood, and made an appointment for next month. I think he is delusional if he thinks I am going to pay him any more of my hard earnd money to treat me like that.
Anyway back to my question, how do you collect parasites? Thank you in advance for any info.