Suggest Treatment For Injured Hamstring And Soreness In Left Knee

I am a 55 y/o male. About 4 weeks ago I felt like I had pulled my hamstring a little, by bending and lifting a lot. I felt like I was just about over it. Tonight, I was working at my restaurant when I twisted to my right to head over to another location and felt a pop behind my left knee, in the same area I had been sore. I can hardly bend my knee or walk. Did I tear something?