What could be cause of aching calves for 2 days now? both legs. also bloated, lower back pain, havent done any strenuous exercise. it is worse at rest?

In the absence of recent strain or overuse of leg muscles, a likely cause is congestion of the veins due to fluid retention &weak venous valves. You may or may not have obvious varicose veins or a family history of varicose veins also. Treatment is elevation of the legs,wearing compression stockings & salt restriction. It's worthwhile consulting a vascular surgeon for evaluation of your leg veins