Suggest Treatment For Knee Injury

I am female, 41 years old and am overweight. I feel down the stairs 3 months ago and landed on my knee on our marble floors. I heard a crunch as I landed. I have not seen a doctor yet. Since that day, three inches below my knee and more to the inside of my leg have been swollen. It took me over a month before I could put pressure on it. It still hurts to kneel on it, but has been bearable. Today, my leg has been throbbing from above my knee all the way down to my toes. Almost a feeling of numbness and tingling. I know something is not right, but I could not get an appointment with the doctor for another three weeks. What could it be and what should I do?