You may also consider looking at your liver and working on a detox program. If you do have parasites, they tend to dump a lot into your system that your liver cannot naturally clean out on its own. I get severe headaches when I'm doing a heavy parasite cleanse and nothing seems to help so I know I can relate that type of headache directly to the parasite problem. I take milk thistle to deal with some of the toxic overload but there are other things you can do as well. Some people recommend enemas but I try to stick to much milder treatments. I would imagine this is only part of the reason you are getting the headaches.
Here is an old post from someone recommending many helpful herbs and foods to deal with the liver. I didn't write this but I've used it as a resource several times: //www.curezone.org/forums/fm.asp?i=482733#i