Problem tenant/States mold exposure

[John Matthew Johnston]

I have a tenant that’s been in my house for around six months. They state that they have upper respiratory like symptoms and nausea for the last month. There was some white discoloration on the basement beams but it was very minor. I bought a commercial mold solution and wiped down all the beams in the basement. Tenant still states upper respiratory and nausea after two Weeks. I told them I do not think this is mold related. I also told them that it is the middle of cold and flu season and my family has also been sick for over a month which we are every year. Just curious about how I can protect myself from any liability from this point out?