From what you have described, I understand that you have knee pain while performing various exercises. It appears that you may have injured the cushions in the knee (called "meniscus") or some ligament injury.
Next Steps
Consult your Family Physician/Orthopaedic Surgeon
Get an MRI Scan of the knee
Health Tips
Avoid high flexion activities, i.e. activities where the knee bends more than 90 degrees