First don't panic. Second you not alone in this boat.
Now let's get down to business.
If you feel them moving about most likely it's a roundworm infection so you are correct here.
Yeah the head region is damn freaky to say the least since not a lot of space for them to move about in the muscle tissue.
Reg numb feeling most likely CNS invasion. Don't freak out here here as well.
It's not in your head and you not mad. It's just very little number of ppl today know complex parasitology.
The scans won't show much when they are in your muscle tissue and they are. Stool tests are a joke. And blood tests tend to be unreliable since much dep on the time/what parasites doing at that time and how your system reacts. The only solid test is for IGE. But docs will claim allergy ROFL!
Don't worry about your brain. One should worry here about eyes and ears. Many parasites well common ones can't pass BBB.
Roundworms can travel all across the body esp if they provoked by something and it could be anything or if the infection was just going on for some time.
I don't think you have trichinella spiralis because you would get a bad muscle pain all over. Having said that you have some type of roundworm like Ascaris larvae crawling about in your muscles. And yes they can.
One important Q. Do you get any pain in chest region? Burning of the lungs?
Reg putting down parasites. Well since it's systemic roundworm infection I suggest ICU albendazole protocol.