Bear in mind that, when tissue swells up due to an inflammatory response. The swelling causes the tissue to push on nerves, and you have a pain perception there, eg: when you exercise, intense exercise may causes an inflammatory response.
If you encounter this problem whenever you exercise and your knees hurt it means you need to do some things to alleviate the condition. You many need additional nutrient in your diet to help promote a healthy inflammatory response. As stated by Dr. Daniel nuzim.