Mononucleosis after treatment?

Hello,

My son had in december a lung tumor removed as well as a month ago. He had now 3 reoccurances of his synovial sarcoma and after 1 1/2 year on the pazopanib, he had temodar and irrinotecan for the last 6 months. Now he all of a sudden has mononucleosis! Really?!? has anyone experienced this or can this be a side effect of all the chemo's in the last 5 year?

This is a pretty common virus in teenagers and young adults. Probably chemo can make a patient more susceptible to the virus since it weakens the immune system. What are the recommendations to handle it? Can he keep receiving chemo or does he have to wait for a while?