If it only happens when you are under stress it can be due to anxiety - anxiety can cause physical symptoms - a knot or pain in the stomach, heart palpitations, chest pains, dizziness, tightening of muscles, headaches, etc. It has to do with the adrenal glands response and the chemicals the boy produces to combat the stress. You may also be unknowingly clenching or grinding your teeth. Certainly have the swollen glands checked for any underlying infection but it could be part of your body's own mechanism to handle the duress your under. You may want to try an anti-anxiety drug - I know - its overly used and prescribed by drs when they don't find anything else wrong - but many people think anxiety is a mental dysfunction and its not - its a physical condition. Its just a thought...of course if nothing medical is found to account for your symptoms you could have a tomogram done to check your joints or have a nightguard made to see if it helps relax your muscles while sleeping.