I challenged son to a race without stretching i am having pain on and off in groin area could that be a hernia also in lower abdominal area?

Race w/o stretching: Could be a hernia or you may simply have pulled a muscle/tore a muscle due to lack of stretching or conditioning. Ask your doctor to have a general surgeon or a sports medicine doc evaluate you.

Could be, but...: It's more likely a muscle strain, but may be a hernia if associated with a lump. Try rest, ice and anti-inflammatory meds (ibuprofen). If that doesn't work, see your doctor for an exam.