Leg pain with sudden onset may be caused by many medical conditions, but the only way to know the exact cause is to see a medical professional, according to Mayo Clinic. Some possible causes of leg pain without injury are deep vein thrombosis, muscle cramp and growing pains.
Minor leg pain with no other symptoms often responds to home treatment, states Mayo Clinic. The best thing to do is stay off the leg as much as possible, and apply an ice pack to the area for 15 to 20 minutes three times per day. A bag of frozen peas also works well. Be sure to elevate the leg whenever lying down or sitting, and use an over-the-counter pain reliever such as Advil or Motrin.
Signs that a person should go to the emergency room include being unable to walk or put weight on the leg, according to Mayo Clinic. Pain, swelling, warmth or redness in the calf, hearing a popping or grinding sound, or a deep cut with an exposed tendon or bone are all reasons to seek immediate medical attention.
See a doctor as soon as possible if there is a sign of infection or a fever greater than 100 degrees Fahrenheit, according to Mayo Clinic. Other reasons to see a doctor include calf pain after sitting for prolonged periods, swelling in both legs accompanied by breathing problems, or any serious leg symptoms that develop for no apparent reason.