Hello there .... since you have mentioned your condition in brief let me tell you if the pain is only on climbing up and down the stairs then the problem lies with your knee cap/patella and not the entire knee joint...... what i need to know is...
1)is the pain more on climbing up or coming down the stairs
2)is it on one side or both (knees)
3)do you have any history of previous knee trauma or injury
4)what occoupation are you engaged in.
For the time being i would advise you to wear knee brace with patella hole whenever you are out or commuting.
Do resort back to me with the answers to my queries and i will give you a detailed exercise protocol required for proper rehabilitation of chondromalacia patella/patelo femoral pain syndrome.
Its very imp. to know its unilateral or bilateral?.
Also since when u r having this problem.?
Do u have any history of earlier injury?
Now as we bend our knee more during stair climbing as that of walking or running so there is more stress over knees .
Better to consult a good therapist l. He will examine the grade of your problem and treatment can be planned accordingly.