The pain you are experiencing is due to the instability your leg is now undergoing. The doctors took out a piece of tendon that essentially holds together. Now over time you have worked your leg causing the outcome; tendonitis. Go get an MRI immediately. You did not tear anything. I know it may feel like that because I experienced this first hand a year after my surgery. Now here I am 2 years later with intense full blown tenonditis. What we can do to help this is PT specifically for hip stretches and hamstring strengthening. However, these actions and movements counteract the new reconstructed ACL. It is sustainable to tearing when you do the PT for this new area. A catch 22 I would like to say. Your pain will subside here and there hopefully you are not in an area with intense rainfall. Tendonitis is a roller coaster. It can get real great and you'll forget about it all, then it'll hit you hard and you'll be reminded if this scandal. Sorry for the intensity of the reality but no one told me this and I just want to give ANYONE a heads up. Try not to be over active. It is a matter if time before you tendons become inflamed.