Because there is controversy about applying heat, I've looked at several sources on the web for information on when to use heat and when to use cold. Heat promotes healing because it promotes blood flow. It also relaxes muscles and eases pain. The disadvantage of heat is that it can increase swelling. That's why cold is recommended right after an injury.
Heat is recommended for later when swelling is gone.
Heat can be useful after about 48 hours. Remember that this information is not a substitute for medical advise. If the pain is severe or persists see a doctor. Once the injured area begins to heal, do M.S.A. techniques. M.S.A. stands for movement, strength, and alternate activities.