I have numbness on my left leg from the knee down and it's been like 2 months already and tonight it just spread to my foot what's happening?

You need a test. If your numbness is only on the left side, you may have a pinched nerve. You should get a nerve test from a podiatry office or a neurologist.
See a doctor. You need to see a doctor and get checked. There are several things that could cause this but things like MS and some autoimmune disorders need to be ruled out.

Related Questions

I have numbness in my left leg from the knee down I have no pain it's just numb not my foot or thigh?

Maybe. Nerve at knee. Perineal nerve might be irritated at knee level. If no weakness in foot or back pain i'd give it a couple weeks then see ortho doc if no better. Read more...
I have numbness. See a neurologist for EMG study that will determine if there is a nerve compression that is causing the problem. Read more...