It's not the flies that is causing this, it's mold poisoning. The flies and Black Mold Gnats which never leave me alone. They lay their eggs all over the house where there is mold or in tolits because the mold comes out in the urin.
If you get a black light you will see the yellow mold or mold period. It could be in the walls and you would never know it. I don't know anyone who can test for the mold and this illness has taking me down for years soi dont have money to have it tested. You can do a test online that can see if you have mycotoxins in your eyes. You can try it one time for free at vcstest.com u believe. Just look up vcs testing and it will tell you if there is a problem.