Thank you for the information,
There are some common causes of such leg pain like venous thrombosis, peripheral arterial disease, electrolyte imbalance, vascular insufficiency, lymphatic obstruction, certain drugs, etc.
As per the symptoms described by you, the chances of vascular cause should be ruled out first.The deep venous thrmbosis may cause the legs to swell and pain while walking.
The other possibility could be the aeripheral arterial disease as the insufficient blood to legs may cause pain.
The certain drugs like crestor ma also cause rhabdomyolysis and leg pain and should be ruled out.You should stop and change to some other drug after consulting your doctor.
You may have the relevant investigations done like serum electrolytes, venous doppler, arterial angiography after consulting your doctor if your symptoms are not controlled.
Here is the link for more information
side effect of crestor
Let me know if you have any doubt.