What Could Discoloration With Swelling In Knee And Ankle Suggest?

I take ISTIN and a water tablet to reduce high blood pressure and they work well. both legs from above the ankle to below the knee are discoloured and slightly hot to touch, by the end of the day my ankles are swollen up, rest at night back to normal in morning. Colourisation has been there since taking the tablets 10yrs ago.