I Have A Very Small (pea Sized) Lump Near My

I have a very small (pea sized) lump near my pelvic lymph nodes. It is moveable and more prominent when I flex those muscles. It isn't sore. I have a few swollen lymph nodes: one behind my ear, one on my head, and one on my neck, but they come and go depending on the severity of my dandruff. What could the lump on my pelvis be from?