Had Knee Drained 8 Hours Ago. Also Got A Cortisone

Had knee drained 8 hours ago. Also got a cortisone shot. Dr thinks it's a torn meniscus. Before injection there was swelling, fluid, feeling of instability and pain in front inside area of knee. After injection kneel feels more unstable and I get a sharp pain in the BACK of my knee when leg is extended. Is this normal??