as per your history you have sustained injury
in left knee about one week and half back.but still you can't walk and suffering from pain.in my opinion you should take hot fomentation,apply crape bandage, some analgesic
tablets and local applicant .But at the same time you should get done xray-Left knee AP,lat. view for bony injury and MRI
Left knee for the tendon and ligaments injury.Future management will depend on your reports.wish you speedy recovery.