Fatty mass removed from neck now it may be infected

I'm 33 and I just had a fatty mass removed from the back of my neck. Surgery went well they took a biopsy and everything came back fine. It was outpatient surgery so I was sent home with a tube for drainage. It was removed 3 days later. I then stared to have a low grade fever and am feeling naseau..i also had a lymphnoid get swollen above incision..so I went back to doc. and he said it was fine and that maybe I was coming down with the flu. It then was almost a week after surgery and I still had a fever and veryyyyy tired. So I went and got a second opinion and he put me on different antibiotics and I ended up being allergic to the second antibiotic. So he told me I had enough antiboitics in me so to take nothing but tylenol for my fever!! It's now been a week and 2 days still have fever of 102 and more lymphnoids around surgery area. I feel horrible and the doctors don't seem to think anythings wrong third doc tor said mybe I have mono but I highly doubt it. I'm very nervous that its infected and could get worse. Anyone have any idea of what I should do?????