Jeff,
Keep in mind that the pop could have been anything. Also, the trainers probably did a Drawer test on your knee. THis is the classic test for an ACL. You probably have laxity in that ligament after the surgery anyway. They usually don't get it as tight as it was orginally. THerefore, that test would have been positive even before you hurt it again. Where is the swelling? and where does it hurt? Let the trainers work with it for at least 4-6 weeks before you do anything like surgery, also make sure they do an MRI and can say for sure that the ACL was torn again. We get a lot of people in here who think the tore something. Usually after a month of therapy they are good to go. Ultrasound, estim and light massage will help the inflammation, take some advil also. Ice and elevate. Get some crutches, the more you use it in the first couple of weeks, the longer the healing time... you need to give it time for the inflammation to reduce. When you try to walk on it, its like ripping the scab off everytime you take a step. You should do that for about 1-2 weeks (On crutches). Give me some more details and I can give you some other exercises to do....

Love ya,
Nathan

PS: We had a great time at D-World only a little rain. Brandi took about 1000 pictures, that is an underestimation. So, I should have some pics to post soon.