Cramp and aching feeling in both legs from knee down sometimes feels like burning sensation. sometimes pain slightly above knee. on iron tablets as lo?

See your doctor : This might be restless legs which can be associated with low iron but a wide variety of other possibilities best sorted out by examining. (Eg referred from back, knee or hip arthritis, neuropathy (nerve problem))

You don't provide: your age, but the likely diagnosis might be different if you are a younger vs older woman. The iron may help, but I would also check vitamin D and magnesium as they could also be low and contribute to these symptoms. If older, the diagnosis of neuropathy, often from Type 2 diabetes, comes into play. You need a good medical evaluation and a few lab tests, I think. Good wishes:)