Could A Painless Pea-sized Lump Above My Left Testicle After Lifting Heavy Weights Be Serious?

A few weeks back I was lifting heavy weights. Started feeling a full ache in my left testicle about 2 hours after my workout. It has since developed into a painless ball about the size of a pea above the testicle. Have an appointment to get it looked at next week but would like some advice as to what you think it might be. Thanks.