How to reenlist with a RE3 code with medical discharge?

I am trying to re-enlist into the Army, specifically this time into the national guard. I was discharged from the U.S. Army for under a medical discharge for a knee issue and the doctor that did my surgery(Knee scope) told me that I couldn't run with my arthritis. When I was getting out, I was told that with the RE3 code, I could re-enlist with a waiver. I attempted once so far, I went to a doctor(A knee and sports medicine specialist) to see what he thought of my knee. He told me I was fine to run, lift, etc on my knee with no problem just that I have arthritis and gave me a letter saying I was good to go in his eyes. When I went to a recruiter, we started the process but hit a snag. He told me since the big army said I was "Unfit for duty" they couldn't go under them and change it. I was told I had to contact the army and have them change it before we could send me to MEPS. I called to the MEB office where I did my med board and they told me that he was wrong, and that since I wasn't in the army anymore they couldn't do anything and that MEPS would have to be the decided factor if I am fit or unfit for duty.

Has anyone ever known or dealt with something like this? My time to serve isn't over in my heart and I know I can do my MOS abilities perfectly. I can run, ruck, jump, and do anything physically demanding. I know there has to be a way for me to be able to get back in, just need help and to be pointed in the right direction.