Ache pain in my legs at night . it hurts a lot especially calves and behind knees . any suggestions ?

See a Doctor: While this could be something like arthritis, there are several other disease processes that can cause leg pain. If it's both legs, it could mean muscle cramps from salt imbalances or even restless leg problems from anemia. You need a full physical exam from a physician, who can then decide what further testing, if any, may be necessary.

Maybe cramps....: I agree with your primary dr.'s answer, but two things also need be considered. Phlebitis is more active at night because of dehydration and immbolity. And the veins of your leg cross behind your knee at the upper calf level. Then finally, a baker's cuyst may be presentm but can be excluded by ultrasound.