Knee clicking when straightening the leg accompanied by mild pain
So a few days ago, i started experiencing some pain in my left knee, and i noticed that whenever i straighten my leg i can hear a clicking sound immediately followed my some pain. At first i thought it was because of how i sit: I'm very tall and i usually have my leg bent at less than 90 degrees, and according to chatgpt (i know it's not very reliable) sitting this way can cause knee problems, but even after changing the way i sit, I'm still experiencing pain. I now have pain whenever i straighten my leg or when i make my knee joint work with a load (doing a squat for example), or whenever i sit in the way i said above. I came to ask for help here because all the sources i found on the internet are giving me different causes: a website is saying it's just air build up in the joint, another one is saying it could be arthritis and another one is saying it's calcification. For reference I'm 18 years old, weight 89 kg and 193 cm tall. (English it's not my first language, so I'm sorry if i made any errors, and thank you in advance for the help)