Ensuring the testicle itself is ok (i.e. no evidence of torsion, infection or a mass), you can consider an ultrasound to evaluate it. I would also obtain blood tests.
If negative, you can consider a hernia or a muscle strain. Obtaining an evaluation by a surgeon or urologist can be considered for an examination of this possibility. Imaging with a pelvic CT scan can be considered as well.
These options can be discussed with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_