How will i know if i have groin hernia?

It won't go away: A bulge or feelings of pressure and swelling in the groin can be a number of things including groin (inguinal) hernias, groin or sports ligament or muscular strain, enlarged lymph nodes (many causes of those), or rarely clots or aneurysms from the femoral blood vessels. Hernia will tend to swell and reduce but will almost always come back and over time enlarge. A good physical exam is all you need.

Lump ;/or pain: Groin her aid are usually associated with a lump which is something like fat or intestines protruding through the hernia defect. This can be associated with pain, but it also possible to have a small hernia you can't feel cause pain. Needs an exam by your doctor, and maybe imaging studies to figure it out. Hope this helps!