Hi, What do you mean by "Intense curve at back"? Is this has been diagnosed as Increased "lumbar lordosis" through X-ray or is just your perception? If it has been diagnosed then, you need to correct it with the help of Proper stretching and strengthening under an expert physio and if it is what you see or perceive then, Get an X-ray done.
It's NOT common to get Knee and back pain while running. If you want to get rid of it, get it diagnosed and get proper treatment.
Next Steps
Get and X-ray done to rule out any abnormality at lower back.
Health Tips
Use hot Bag whenever u feel more pain, you must take external help for long term.