Hi,
Greetings s/w engineer,
Based on your BMI you are little over weight. Probably you may have little pain while stepping up was due to knee lock. Anyway please follow the below things carefully.
1. Apply RICE method for acute condition.
2. Once pain subsided start the isometric exercise to 'Q'ceps for 3 weeks
3. Stretching to calf and Hamstring muscles
4. Use knee brace or knee cap to avoid unwanted movement
5. Start MCL, ACL strengthening
6. If you play regular food ball than you have to strengthen core muscles
Next Steps
Consult near by physiotherapy clinic
Health Tips
Avoid long standing
Avoid lifting heavy weight
Avoid cross leg activities
Avoid steps, Use lift in office.