This is a good question. There are many possible causes for your symptoms so it is very important that you make an appointment with your primary care doctor
to discuss your symptoms and have a full history and physical. One possible cause for your symptoms of pain, tenderness, and burning followed by a rash is herpes zoster, more commonly known as shingles. This is caused by the chickenpox virus that was dormant in your nerve cells and has not become reactivated. It usually occurs in a band on one side of your body. It is more common in elderly people or those with a weakened immune system. Shingles is treated with antiviral medications. Other possible causes are a pulled muscle in your calf or referred pain from your knee. Pain could also be due to a blood clot in your calf, known as a DVT, or deep vein thrombosis. The tiny red spots could be blood vessels that have broken (due to swelling) or perhaps an allergic reaction to something you applied to help the pain, such as icy hot? Again, it is very important that you seek medical care as soon as possible to get a correct diagnosis and appropriate treatment.