Welcome to Healthcaremagic.
The pain you have in the knee appears to be due to ligamental injury
.Such an injury will cause pain while walking and climbing up the stairs.
Immobilization for a week or two by tightly strapping the crepe bandage would heal the injury and put an end to the pain.
Do apply DICLOFENAC
gel over the affected area for temporary relief from pain.
Hope I answered your query.
Wish you good health.