I have a tiny hard round shaped lump above groin muscle underneath the skin. It has slight pain when I wear tight clothes. Not ingrown hair it's deep?

See your PCP. You've described it so well, and now it's time to see your primary care physician, or gynecologist to identify what it is, and discuss your options. S/he may need to ultrasound it if it's large. If it's smaller, they will have a differential diagnoses of what it is to determine if it's cystic or lymphatic by location. I would refrain from wearing tight clothes/jean, until you determine what it is.