Knee won’t stop clicking, and starts to ache after too much movement. I also have to stand/move at

I don’t know exactly what happened to my knee, but for reference, I am overweight and 25.

I might’ve gone too hard at the gym - maybe when the using of the stairstepper or incline treadmill? maybe I over stretched myself

It clicks constantly and it feels like something is “catching” wrong when I bend. After a long time of standing/moving/walking around, the ache sets in. It’s located on the inner-side of my knee. It’s not too painful (I’d feel stupid for calling out sick for it), but it throbs and aches when I can finally get my weight off it.

I’ve skipped the gym for a week to not aggravate it, but it hasn’t improved at all. I still have a dog to walk and a retail job that requires standing for virtually my whole shift, so not irritating my leg is difficult. I also have been favoring my other leg when standing to take the pressure off, but this leads to my other leg wearing out.

It’s not air bubbles like the kind you get from cracking knuckles. Online says this clicking is harmless if it’s not immediately painful, but it does eventually become painful SO therefore it is harmful. But I literally cannot figure out what to do to fix it. Anyone know how to fix this?