Well the report came back from the pathology. They are calling Magic's issue as Histiocytosis, probably at this point the reactive type. The vet suggested the. UC Davis Website for information.
From reading this site and others, it does seem like at this point reactive histiocytosis fits his symptoms, as the most recent huge lump is now receding. I do have more questions for my vet, but I am in the process of creating a list at this point. I think though that we are going to start keeping track of things to see if we can poinpoint what is causing the reactions. it seems like the last one started right after he got his monthly heartworm meds. Coincidence? Probably, but its going to bug me so I will need to really track this.
I will try to post a new picture of Magics much smaller lump tonight.