Hi, thanks for writing to HCM.
From the description, I suspect "Patello femoral arthritis" in you. This typically manifests as pain in the front portion of knees especially while going up and coming down a staircase. Nothing to worry as such about it as this problem is more often seen in younger individuals only and can be managed with medicines and physiotherapy
I suggest you to consult an orthopedic surgeon and follow his advice.
Hope this helps. Good day