First of all, consider the fact that he's conning you, because you didn't go to a doctor, and haven't really been tested.
If you do have all these parasites, don't pay the money to that douchebag, go online and order some herbs:
Black Walnut Extract
and you must obtain Iceland Moss.
Oil of Oregano
Eat, literally eat fresh garlic, chop it up and eat it. It will burn like a sonofabitch, so get this shit and have a nice tall clean glass of water handy.
Ultimately the above remedy is for tuberculosis, but should work for you.
It won't cost you $300, but you will have to take a good amount of it every day for at least a week.
Be prepared to taste really bitter nasty herbs and drink a shit ton of water. But you have to do it everyday.
If you have kidney problems, do NOT take the above remedy.
The Wormwood/Absinth extract is the strongest of the above, it will make you feel a little funny, and drink plenty of water within a couple hours afterwords.
The Elecampane and Iceland Moss and Garlic will go to your lungs to help kill off and treat whatevers in there.
Schizandra Berry will also help detox, and go to your lungs.
The french used fresh garlic in the Middle Ages, but we're not talking about cooking with it here, you have to eat like at least one clove of fresh garlic maybe twice or three times a day.
It may mess with your bowels a little, but do you want to suffer and die, or just have the shits for a couple days?
You might also try clove, or nutmeg as well, and Colloidal Silver, but one only will not do the trick. You have to flood your system with nasty herbal chemicals which is essentially the whole idea, you have to kill the parasites, and then flush them, burdock, dandelion, and schizandra/schisandra will help flush it out.
Keep your water constantly handy for the taste and the effects of these herbs.