Small bump on the left testicle (inside the scrotum) near right back that moves around. if i would guess size, i'd say 1/3 a pea or less. dangerous?

Probably bot: Its pobably benign but a new are in the testice warrants a look, and probably an ultrasound, by a urologist. Most likely it's define, google testicular cyst.

Testicular Exam: You need to have a physician examine your testes. Young men aged 15-35 are at highest risk for testicular cancer. That said it is still rare. It is likely a one of a few lesions: epididymal cyst/spermatocele, appendix testis, or some scrotal cutaneous lesion (like an epidermal inclusion cyst among others). It is likely benign, but the slight risk of malignancy behooves you to have it checked.