Hi I'm 18 and a dance every day and I use th gym alot recently I have noticed a very sore pain on my knee on the back the knee has purple veins that are quite prominate and when I bend the knee joint I'm in a lot of pain and find myself shaking just so I don't feel it , unfortunately I have also just started to get the same thing on my quadriceps please help should I see a doctor as it's been like this for about 3 weeks.