I have my left foot swollen for about 6 months no apparently reason. x-ray, nuclear test, doppler and finally mri doesn't show anything. need help!

Unilateral foot : Swelling? I assume it is not painful. It could be lymphedema, caused by anything that interrupts lymph drainage from the foot. If you are diabetic, you could have decreased sensation in the foot and traumatize it repeatedly without knowing, condition called charcot's foot. But not likely with normal mri, which is a very accurate imaging test. I am stumped, sorry.