If you are quite sure you have a worm or similar parasite infection and the doctors refuse to treat you or diagnose you with such there are a couple things you can do. And this is if your problem is life changing and you are out of options. First of all you have to play their game. They are usually board certified and/or work for a hospital so everything they advise you on and prescribe is closely monitored -- it goes on their record. So you can be VERY sure they will not go against conventional reccomendations for a given condition...especially something like a parasite infection. So how do you play their game and win? The first thing they ask you is "Have you been to another country recently?". In their pseudo logic cookbook of proper diagnostic reccomendations they are looking for PROBABILITIES that you have a parasite infection. So make this work in your favor. Get yourself a nice vacation to a worm infested country. I suggest don't go swimming if you do go to such a country.
Long story short: reverse engineer a worm infestation diagnosis. Take what a doctor is taught to be the highest probability of parasite infection: geographic location, activities at that location...etc. You can tell him what you want. Bingo! you just helped him not get into trouble for prescribing you anti-parasite medication! Like I said you have to play the game, these are people that have worked extremely hard to get their job and license, they aren't going to risk that on you.
If they demand physical proof - a specimen of your infestation. THEN GET THEM A SPECIMEN. You know what I mean? where there is a will there's a way. These doctors are just people that don't want to lose their jobs, because the medical board in each state are like the German NAZI's sticking their noses into every aspect of the doctor's practice. Make it so the doctor has a full proof explanation for prescribing you medication, and that is not going to include going off your story or your troubles or stated symptoms. There are a trillion conditions that mimic the symptoms of a parasite infection. You will have to provide specific undeniable proof. If your life is on the line then your options include: getting infected on purpose, this time with PICTURES and witnesses. make it a fool proof slam dunk win if it ever goes to court.