Knee pain

Patient: A few days ago i had physicals for my sports college course all day and my legs hurt a bit but then they were fine. yesterday i was in the garden pulling weeds and i bent my knees down and now my right knee is throbbing. its really hard to walk on, i cant bend it or straighten it properly and sometimes i have these moments where it goes all numb. my mom isnt home at the moment and all i have done really is taken some pain relief and it hasnt worked, its only swollen a tiny bit, help please.

Doctor: