Since when is the pain?
How severe is the pain on the scale of 0-10?
Is there any tenderness, bloating, gas, urinary burning, increased frequency of urination, constipation/diarrhea, nausea/vomiting?
Any unprotected sex?
Any significant past medical history?
Following are the possibilities of the pain;
1) Lower abdominal muscle strain
2) Groin strain
Warm compresses, Ibuprofen, local analgesic cream and rest (no exertion or sporting activity) are likely to abate your symptoms.
Please feel free for your follow up questions.