Once I got over the shock that you might think more people here are familiar with the testicle size of a 50 pound dog than a pecan, followed by your admission that it feels like a dog testicle (which indicates you've felt one), I thought I'd put something hopefully productive into the conversation....
Had a buddy who over did exercise and ruptured a small blood vessel in his leg which was slightly painful but not excessively and seemed to be a globulous lump. Turned out to be a rather large (he was just feeling part of it) blod clot that left untreated could easly have killed him.
Weird lumps need a doctor's attention, if only to rule out possible problems.
angela