 [ Symptoms ] can poison ivy rash return same place after 2 months  rash returned same places on arms after 2 months since had first rash  have not been any where near any plants no pets to come in contact with poison ivy any one ever hear of this happening [ Disease ] valtrex will not help a rash related to mononucleosis there are thousands of medical conditions that can result in a rash so it would not be wise to associate your son is mono with your rash the rash seen in mono does not usually itch since i cannot see your rash and examine you over the internet i would advise you to see a medical provider so you can be properly diagnosed