Perinuem lump pain in ischial muscle.

Hi i have some problem with my perineum.its been 2years when i noticed small soft lump inside my perineum.it can't be seen bt felt when pressing deep..but now it can be felt easily bt still its under deep tissue.IMPORTANT- LUMP BECOME VERY SOFT WHEN TESTIS COME IN RELAX POSITION AND GET MINOR HARD WHEN TESTIS ARE SHRINKED OR ELSE I CAN SAY ITS GET HARD WHILE ERECTION..it never pains and its very soft as well but now creating discomfort when wearing tight jeans or undergarments..from last many months iam feeling pain while pressing ischial tuberosity but lump never pains.when i sit on hard surface i feel pintching pain in near ischial tuberosity n also with tight clothing.i dnt have any lympnode urine problem..the lump from last 2.5 years it jst slightly grown but doesn't bother me..the bothering me is pain near ischial tuberosity muscles while pressing them hard..plz tell me wot it can be because iam veey much scared of cancer.i also feel pain in left scrotum line and groin only sumtym