My name isXXXXX am another expert here on Just Answer and I have 8 years experience in orthopedics. Thank you for using Just Answer. I am happy to help you with your concern today.
It sounds as if you may have developed what is called chondromalacia patella. This is often called runners knee.
Chondromalacia patella is a disorder that is the breaking down and softening of the cartilage that lays behind your knee cap (patella) The cartilage is supposed to slide smoothly along the knee, but as we age or have an injury the knee cap can rub against one side of the joint causing breakdown of the cartilage.
Symptoms can include a dull aching pain in the front of the knee, pain with walking, running, climbing stairs, kneeling, squatting, sitting for prolonged periods and grinding with extending the knee.
Treatment consists of rest, anti-inflammatory medications, bracing, physical therapy and occasionally surgery is needed to scope the knee and clean up the cartilage.
Another possibility is a meniscus tear. If you have any locking or catching or pain in the middle on the inside or outside of the knee you may have a meniscus tear. The meniscus are c shaped shock absorbing cartilage that lies between the bones. They are torn easily. Treatment is usually surgery.
My suggestion to you is to rest the knee for 2 weeks (no impact running, jumping), take 400mg of ibuprofen four times a day with food (watch for stomach upset) and purchase a hinged knee brace ( a neoprene brace with hinges on the side) which can be bought at super stores or medical supply stores. You should also do some stretching and strengthening exercises, here is a website that shows and explains the exercises that should be done, however if 1 particular one increases your discomfort then do not do that one http://orthoinfo.aaos.org/topic.cfm?topic=A00564. If after 2 weeks your symptoms are not improved or have worsened, please see an orthopedic that specializes in the knee. They will do x-rays to look at the bone and an MRI to look at the cartilage, ligaments, etc. They can also give you a prescription strength anti-inflammatory, I suggest Mobic. Treatment will go from there depending on what the imaging studies show.
If you have any further questions please let me know. If not, have a great day and I hope you feel better soon!