When I bend over to pick something up, not necessarily bending the knee. but I can hear a tearing/popping type sound at the bottom of my knee cap. Its usually not painful, but discomforting. Today it was way worse than usually and hurt for a breif second.
Hi I am Chat Doctor. .  In my opinion you may have a kind of tendinitis or your cartilage surfaces become more rougher or ligaments tightening.  I do not want you to be worried unless these sounds are painful, you may try to decrease your weight, avoid heavy lifting, vigorous movements, bending your knees for a long time and bad sleeping and sitting postures.  Using hot massages with topical gels of anti-inflammatory and some physical activities like morning jogging will be helpful.  If these sounds became more painful I recommend you visit your physician for proper evaluation and management and prevent further complications. Please click and consider a 5-star rating with some positive feedback if the information was helpful. Wish you good health, Any further clarifications feel free to ask.