This is likely to be adductor strain. Please read about it (this resource is technical, but gives an overview of the problem);
A mild pain can be managed at home, but moderate to severe pain and progressive symptoms would warrant an active help by a physical therapist or MD in physical medicine and rehabilitation. Following measures are recommended for the treatment;
1) passive stretching of the affected muscle after application of sprayed vapocoolant.
2) physical therapy; simple muscle stretch, augmented muscle stretch, post-isometric relaxation.
3) deep electrotherapy; iontophoresis, phonophoresis, short wave diathermy, electrical stimulation, high voltage galvanic stimulation, biofeedback.
4) local analgesic patch / ointment / spray
5) anti-inflammatory analgesics; Ibuprofen (Motrin / Advil)
6) ischemic compression therapy; pressure on the points
7) mild massage
8) steroid shots
You may meanwhile apply cold compresses, local analgesic spray and take Ibuprofen for 3-5 days. Also try to avoid the painful activities which helps in healing the strain.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.