These symptoms are very worrying. I would strongly recommend that you see your primary care doctor
in order to have this evaluated. If you are not able to see him or her in the near future (within a week) I would even recommend going straight to the emergency room. While there may be no abnormality, this could be a sign of a serious disease and therefore would require these "bad" causes ruled out.
There are three major causes of lower extremity swelling as you describe (although there are certainly more than three). The first is heart problems or a weakened heart muscle. Given your heart symptoms this would be a concern. Your heart problems could be caused by abnormal hormones (specifically a disease known as a pheochromocytoma) although there could be other causes. This should be evaluated. A second major cause would be kidney problems. This can cause swelling as well as bloody urine. A third cause would be liver problems.
As mentioned there are other causes. Clots in the blood vessels can cause what you describe. In addition, there are some infections to worry
See your doctor urgently. You are a young person and these problems should be addressed. Good luck!