Interesting feedback.
The knee and the hip share a common innervation, therefore injury to the knee can manifest as pain in the knee or the hip, and vice versa. Therefore, the pain in the hip may be referred from the knee, may be to due injury in the hip itself, or may be due to changed gait etc. forces, compensating for the knee injury.
My advice is to see a doctor, and get it properly sorted out.
RD.