why doctors dont understand?

I dont understand why doctors cant figure this out about worms parasites and flukes. If you go to a doctor and complain about parastie related stuff they will do all these exams like endoscopy and colonoscopy and when they are negative they will just throw their hands up in the air. Its only after aggressively reading and taking herbs on my own did i find out that my problem was parasite related and in my opinion its the only way to treat a long term parasite infestation