You ultimately are going to have visit a doctor (probably an orthopod sports medicine specialist) to get an accurate diagnosis.
But the subscapularis muscle is attatched to the underside of the scapula, and inserts into the humerus (upper arm bone), and is one of the four muscles that makes up the rotator cuff.
The following is taken from sportsinjuryclinic.net: http://www.sportsinjuryclinic.net/cy...scapinflam.htm
"It is mainly throwers that injure this muscle. A partial rupture of the muscle is more common than a complete rupture but the partial rupture will often heal with inflammation.
Pain when moving the shoulder especially when the arm is raised above the shoulders.
Pain when you rotate the arm inwards against resistance.
Pain when you press in on the tendon insertion (difficult if you don't know where it is exactly).
What can the athlete do?
Rest until it is not painful.
Apply heat and use a heat retainer.
See a sports injury professional who can advise on rehabilitation.
What can a sports injury specialist of doctor do?
Prescribe anti-inflammatory medication such as ibuprofen.
Apply sports massage techniques.
Prescribe a programme of mobility, flexibility and strength training.
If you have a partial rupture then as long as you look after it you should be back in training within 3 weeks. However if you think it has started to become inflamed then you must rest or the injury will become chronic requiring you to rest for months."