If you have not suffered any kind of trauma to your heel, it is extremely unlikely that a fracture is the reason why your heel is swollen and painful. It normally takes a significant impact to fracture one's heel. Of course, if you are past the age of 50 or if you have osteoporosis, a fracture is possible. If this is the case, you should try to think of even any minor impact that your feet may have experienced recently. With age and osteoporosis, the bones tend to become much weaker, and even a mild bump that you barely noticed can cause a fracture.
If you suspect a fracture, you should simply get an x-ray done. There is no other way to confirm or rule out a fracture, except of course in the case of severe fractures, where simply looking at the injury makes it obvious. If it turns out that you do have a fracture, your doctor will advise you on what to do. You will quite certainly need to stay off the affected foot for at least a few weeks.
Even if it is not a fracture, resting your foot seems like a good idea. You have not mentioned how long you have had this problem or how severe the pain and swelling are, and in any case it will probably take a physical examination to really understand the problem. However, you can try staying in bed for two or three days, and see if the pain and swelling decrease. It may be some kind of insect bite, or perhaps you have simply strained your foot too much. If there is no improvement after a couple of days of bed rest, the best thing to do will be to visit your doctor, as there are too many possibilities.
answered by G R