Hi: I agree with Jenn. First go see a doctor. You could have some issues that can be easily treated. I do have Leukemia, and I never had any symptoms. They found mine with a simple blood test by accident. My knee hurts too, and its Arthritis. Do not try to diagnose yourself, and if you keep worrying you will find you feel more ailments from nerves. Please get a good physical with your doctor, and let us know how your doing.
Honestly, if you haven't done so, please see a doctor. There is no way of telling what is going on until someones sees you and orders the appropriate testing such as a CBC (complete blood count) and a few others to start with.. Depending on what he or she suspects, then more tests may be ordered. Your symptoms can be caused by many conditions so it really is in your best interest to see a doctor about your concerns.
Jenn