by the way if it's center of the knee ACL tear sounds just about right. If you've been running with an ACL tear and this has happened a couple of times it is most likely your meniscus has been affected. Also, if you gained some weight in those 2 1/2 months, most likely the pressure you are imposing on your knee with the affected meniscus is likely to cause severe knee pain.
I am 17 and I have had my meniscus taken out and have replaced my ACL with my own hamstring. When my meniscus was taken out my doctor told me that I would have arthriitis (or would most likely have arthritis) by the age of 20. I was a heavy athlete, but not as a profession though. Also, I also experienced a sharp pain during my injury. I do not know if this applies to you however you can tell when your knee buckles that the sharp pain is due to the tearing of the ACL. This does not only happen in sports but it can happen in normal daily activities. Why? Because it takes a certain position and a certain amount of strength, and the criteria for it doesn't necessarily just apply to sports.
Also in terms of suggestions, you have to be aware that cold compression is worse than hot compression. You need to keep the blood circulating. Raising your knee helps with this too. Aggressive therapy is horrible in the way that you need to give your muscles a break from all that exercise. When you can feel a stretch you should just resort to resting with hot compression.
I really hope this helps. It *****. The whole experience and everything. I'm not a doctor but I have done tons of research and have gone through this myself. I hope this helps. Let me know how you do :)
Well, without a clinical evaluation it would be difficult to determine the cause of the symptoms. Knee issues could be caused due to a few reasons such as patellar dislocation, chondromalacia, fractures, injuries to the internal ligaments/ menisci, infections/ inflammations, arthritis, bursitis, tendonitis, cyst formation, iliotibial band syndrome, osgood-schlatter disease, bone growths/ tumours, nerve injuries/ impingement etc. I would suggest an evaluation by an experienced orthopedician at this time for an accurate diagnosis and appropriate management.
Hope this helps.