My college roommate infected my clothing with fleas as a practical joke. They look like little black dots and are noticeable after they hatch there eggs. Needless to say, I no longer talk to that roommate.
it could be something like fleas, "human fleas" are invisible to the naked eye. maybe crab louse because they seem to prefer the body hair.
there are many different types of bugs. probably not HEAD-lice and it's absolutely not scabies.
generally they fear the heat and the frost, he could try to shower his head with ice cold shower (or boiling hot), reclined in the bathtub. to rinse them off. the temperature is important because if it's mild it won't bother them.
keep the house clean and hoover the floors until they are all gone. put all his clothes in the washer in 60c
Look us morgellons, crab louse and scabies to see if any of these sound like is symptoms. Good luck!
It could be a lot of things. Including a wide verity of mites. Lice or scabies would be worst case scenarios. But these body mites require time to lay eggs and hatch before symptoms become widespread. You said he has been experiencing the symptoms ever since he was in the unsanitary house. This decreases the chances that it is some type of body mite,
It it's flees you would know right away because these are larger bugs that are visible to the naked eye.
I would suspect that it is more likely a reaction to some sort of chemical that was in the house. If the house was ever used as a meth lab or something an allergic reaction could happen right away. Not to say that's the only way some sort of chemical could have gotten in the house.
It really could be a lot of things. If it doesn't resolve itself in another week, or gets worse, I would suggest consulting a doctor.
Typically, if it is a toxin, it should take no more than a week to resolve itself. If it doesn't, it may be something worse like mites.
Hair doesn't need to be long to have lice. Go to your pharmacy and ask for a recommendation from the pharmacist. He will either offer you the medicated shampoo for lice, or make another suggestion. You might have him wash his beard with Listerine; my mother-in-law did that for dry scalp and dandruff and it is a refreshing rinse that will not hurt him. If neither of these work, consult a physician or dermatologist; he could have a skin condition and need to shave to be able to treat it adequately. Consult a professional if it continues.