Suggest Medication For Sharp Knee Pain Due To An Injury.

Hello doctor,I am Rik,17 years old,179 cm tall and my weight is 68 kg.I got tripped during an amateur soccer match last sunday and landed on my left knee.I heard no 'pop' sound but felt a sharp pain whenever I tried to fold my left knee.Then i came back home walking all by myself.I could walk properly but was having a sharp pain when I tried to bend the knee
I have been wearing a brace for five days now and the pain is much less.I can fold my left knee to a much greater extend although not fully.
Do you think i have a ligament tear?
What investigations do you suggest?
What shoiuld I do in case I have a ligament tear?