The inside of my knee hurts when i straighten it or put weight on it. it also pops a lot, why? and what may help?

Possible meniscus: You need to be seen by an orthopaedic surgeon to evaluate your knee for a possible meniscus tear. You need an exam and an mri. If torn, arthroscopic surgery can trim the tear and improve your symptoms quickly. This is a picture of your meniscus seen here. It is the shock absorber between the femur and the tibia cartilage surfaces. This one is normal.

Many possibilities: The description isn't enough to be conclusive but these symptoms could be from bursitis, arthritis, meniscus year, or sprain/strain. See your doctor for an exam and treatment plan. Meanwhile, rest and ice may help.