i also have a similar problem, left testicle has a slightly smaller than pea sized lump at the base where the epididymus attaches to the teste. Doctor checked it out and said it was a cyst. It causes an ache and teste is very sensitive and painful at the slightest touch. He gave me a prescription for antibiotics but told me it would probably pass within a few days, but if not to start the antibiotics.Doctor also suggested an ultrasound if no improvement developed.

If I were you, I would be getting a second opinion from another doctor, or demanding the ultrasound, just to make sure.