Hello there, I have read your question, The site of pain you are mentioning and doctors diagnosis is totally different. Dr has told you Groin pain, which means Adductor muscles have been injured but according to your complaints (pain below his knee) my diagnosis is totally different. He might be suffering from Jumpers Knee. Jumpers knee or patellar tendonitis is pain in the tendon which attaches the kneecap or patella to the top of the shin bone or tibia. It is usually an overuse injury caused by repetitive strain. Patellar tendonitis can be a tricky condition to treat and requires a substantial period of rest and a thorough treatment and rehabilitation program. In the most severe or persistent cases, surgery may be required. Treatment for patella tendonitis consists of reducing the initial pain and inflammation through rest and ice followed by a rehabilitation program which will include eccentric strengthening exercises. Home treatment- Apply cold therapy on a regular basis, especially during the acute stage which is usually the first 24 to 48 hours and after any form of exercise. Professional treatment- anti-inflammatory medication e.g. ibuprofen. Do not take ibuprofen if you have asthma and check with a doctor before taking any medication. A patella tendon taping technique can be used to relieve pain and take the pressure off the tendon in the same way a patella strap works. A professional therapist may use electrotherapy in the form of ultrasound or laser treatment to reduce pain and inflammation and aid the healing process. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing you Speedy recovery.