I saw an Infectious Disease doc in Dec. He ran tests on my immune system, and the results inidicated what Peacesoul said - my Tcells were above the normal range. He referred me back to rheumatology and my pcp concurred that it showed my immune system is hyperactive. I'm taking Plaquanil but not an immunosuppressant. Several years ago I went through a period where I did catch anything that was going around - especially respiratory/sinus bugs. It was miserable. We discovered that not only was I dealing with a mold issue at work, but we uncovered some in our own basement. When those problems were eliminated - it seemed my rate of infection also decreased dramatically.
I only bring this up to suggest you think about whether there might be something in your environment triggering these illnesses or that are keeping you from fully recovering. Mold is a common culprit.
diagnoses: mono 1972; postviral CFS 1997; fibro 1998; UCTD (dx limbo) 2007
meds: Plaquenil 400 mg, occasional low dose xanax for sleep aid, artificial tears w/ ointment at night, Advil/aspirin prn