my first diagnosis is Chondromalacia patella - which means softening of the patellar cartilage. There are many reasons for this condition - most important being hormonal imbalance/ pregnancy.
Next Steps
You need to consult orthopaedic surgeon. if he confirms that you are having chondromalacia patella by clinical examination, he will prescribe to NSAIDS and teach you quadriceps / VMO exercises, and ask for physiotherapy modalities
Health Tips
avoid squatting, sitting on floor or cross leg, climbing steps etc which would increase the symptoms.