Swelling feet ,have low blood pressure so I can't take water pills also have red splotches almost purple on lower legs

CALL YOUR DOCTOR. Keep your feet elevated for now, several times a day, and avoid strenuous work. You might have any number of blood/vascular problems.

Age, weight, and blood pressure all affect our legs easily, because the legs are farthest from the heart and have to work the most, especially when we are vertical, to pump blood back to the heart. There are valves in the leg blood vessels that open to let blood get pumped upward, and then close to keep it moving upward. Red splotches in both legs can be a sign that your valves are wearing out. But the splotches and edema can be signs of many things, and only your doctor can tell you with an exam and tests. If one leg is quite different from the other, your doctor might be more concerned about a clot.