Mastodawn

Knee pain on stairs is rarely a "rest and hope" situation. Usually: weak glutes + tight hip flexors (hello, desk life) dumping load onto the knee joint.

8 min, 3x/week, no equipment:
→ Side-lying leg raises – 2×12/side
→ Couch stretch – 90s/side
→ Slow step-downs – 2×8/leg

Give it two weeks. The knee is often just doing someone else's job.