23 yrs. had minor knee pain d timer test was 620. normal is 499. next day ultrasound at hospital no clot. d timer was normal. still worried why 620?

Lab tests change: The first rule when you find a abnormal blood test is to recheck it. The reason is sometimes it is abnormal for technical reasons, and you want to make certain whether there is a true medical problem if you see this result. I cannot explain your symptoms, and I'm uncertain the D dimer would be the first thing I look for, but since your leg shows no blood clot. You should discuss with your MD