My 2 years old show high monocytes on cbc constantly, enlarged lymph nodes on the side of the neck and temperatures around 99. what could be?

Viral vs other: How long the symptoms have been going on? If this is new- just for 1-2 weeks likely it is a viral infection. However, if this has been going on longer, and in addition to above symptoms- your child also has other things like pale, anemic, bleeding, rapid enlargement of the lymph nodes etc- it may be other thing more serious. Bring your child to pediatrician for follow up and further evaluation.