False-Positive Monospot Test?

Hello all,

My boyfriends father has lupus, and my boyfriend has recently (in the past year) come down with a whole host of symptoms that look like lupus. I finally got him to go to a doctor, and one of the tests they performed was for mono. His monospot just came back "slightly positive" but I know that lupus can cause a false-positive. First of all, if it were mono, I would most likely be sick. And he doesn't have a fever or sore throat or the classic mono symptoms. What he has is a terrible headache that hasn't gone away in 2 months, shaking hands and arms, knees he can't stand on for more the an hour, extreme fatigue, sleepless nights, weight loss, appetite loss, sensitivity to cold, and increased thirst. I am super worried that he may have lupus and that it is more than just mono. Input?

I have been asking several questions. I don't want to be the nagging girlfriend, I just want to support him and make sure he is okay. Plus, he and his family avoids doctors at all costs. The fact he went and got checked out was a miracle..

As far as joint pain, I know he has it in his knees, severely. He may have it elsewhere but he keeps those things to himself and never talks about issues he has let alone sees a doctor.