How To Treat Sharp Pain And Lump On Left Leg After Running?

Hi. I am a 25 year old female. 66 inches 220 lbs. healthy with the exception of my weight, but i have already lost almost 40 lbs through diet and exercise. I recently started a running program. it has been about a month. on the inside of my left leg below my knee i have a very painful lump. it is not visible from the outside. it hurts constantly, and when i press on it i get a shooting pain up and down my leg from my toes to my hip and my foot begins to go numb. furthermore when i run my feet go completely numb, and sometimes my entire lower legs go numb all the way to the knee. do you know what could be wrong?