Where is the lump located in the scrotum? Any lumps like these should be evaluated by a doctor to be sure. A testicular cancer lump would be directly connected to the testicle and should be checked right away. I hope all goes well.
... it may be what my boyfriend refers to as a "boil in the bag." It goes away on its own, over a period of time (a couple of weeks)... or, you can go to a doctor and have it examined, lanced, drained and treated with antibiotics.