Spleen 2cm swollen. normal blood work. had mono 8 months ago. glands a swollen on neck but have sore throat. can mono re-activate?

Normal with mono: Yes, mono can reactivate and spleen can fluctuate slightly in size due to various other physiologic issues. I wouldn't be terribly concerned. Have US repeated in 6 months.

Insignificant: I would consider your findings insignificant in the scheme of things. There is more than one agent that can trigger a mono like syndrome & that amount of speanic change is not that impressive, whether found by a good physical exam or other means.The CDC debunked the idea of a "chronic" mono more than a decade ago. You likely acquired another viral illness that will pass.