As Krimpet said, many have to deal with this. EBV - the virus that causes Mono - never goes away, the body has to keep it under control (dormant). So any time the immune function falls below a certain level, there are several viruses that most people carry that can become reactivated and produce symptoms once again.
There are antivirals that your doctor can give you, or I choose to use Lysine, as there are very few side effects with it. I've been using it for the last 6 years to keep several viruses under control.
Herb only treatment for Lyme & Bart ended 12/11 - no active symptoms for 2 yrs -Herb only treatment for Babesia ended 12/12www.healingwell.com/community/default.aspx?f=30&m=2977364
Had Lyme, Bart, Babs, RMSF, Ehrlichia, Myco, Anaplasmosis, EBV
New Lyme case 8/2014 - Healed 1/31/15 - unknowingly had Asymptomatic Babs and Asymptomatic Bart, being treated now though (2/2016)