Advice needed on stacked septum!

I’ve had my septum pierced for almost 12 years, no issues and rarely changed the jewelry, always kept a 16g ring in. I wanted to change up my look and do a stacked septum look (I had a fake stacked looking ring in for a year and wanted the real thing). I bought a pack of 10mm 20g stainless steel rings and kinda went for it. My piercing is so old there was a lot of give when putting smaller rings in, I originally got 5 rings in. Felt tight but no pain, and I knew they would settle from what I read online about stacked septums. After a few days, it started to hurt, which i anticipated but then it wouldn’t really subside for a few days so went down to 4 rings to get some relief. However this process has repeated to now I’m two weeks in and down to 2 rings and still having some pain. I’m not a stranger to stretching, I’ve stretched my lobes, but I know that’s not the same kind of tissue.

What am I doing wrong? Or do I just thug it out? I really want to stack my septum, the right way. Am I just being impatient with the pain? Is it supposed to feel like I got punched in the nose? lol