Take a break from the activity that you are doing. Continuing with it despite warnings from your body can make things worse. Our body has a certain limit. Do not over exert it beyond this limit. This does not mean that you end all physical activity. Continue with your usual activities but give this muscle part a break. Support the muscle using crutches and slings.
Place ice cubes in a towel and make a compress out of it. Press this compress to the torn muscle. The cold compress will numb the area and reduce the pain. An ice wrap can also be bought and re-used. Ice bandages also provide support. They also reduce the inflammation by reducing blood flow to that area. Apply cold compress whenever the pain threatens. Constant ice compress helps in a speedy recovery with lesser pain. However, make sure that you always apply ice packed in some fabric. Ice should not directly touch bare skin. The treatment for torn muscles is cold so avoid any hot treatment for this.
Take an anti-inflammatory pain killer like Aspirin which can relieve you of the pain. It will also prevent the area from swelling. Ibuprofen and acetaminophen are also effective against such pains.
Stretch the muscle regularly and lightly to keep it moving. However, do not put any strain on the muscles and allow them to recover on their own. If you put any new strain, the process of healing can go on for longer. If you do not show any signs of improvement in a week, you should consult the doctor for professional help.