Apart from these it can also be a pinched nerve. Since you can feel a swelling, swollen
lymph nodes should be ruled out.
lymph nodes in the groin could be due to STDs (e.g., gonococcal infection, herpes simplex virus, syphilis, chancroid, granuloma inguinale, lymphogranuloma venereum etc), infection in foot, dermatitis in pelvic area, boils in pelvic area etc. Other than this pelvic malignancy and lymphoma could be the other causes. It is difficult to comment beyond this at this stage.