Is something wrong with my ear stretching process?

Just 2 days ago, I went from a size 8 gauge to a size 6, after previously trying to put in a 6 after 2 days**. It got infected, so I switched back to the 8. 2 days ago, I made the switch with a bit of pain after waiting a few weeks, but then it didn't hurt at all when I tugged on it. For gits and shiggles, I decided to try and put in my 4, just to see if it would hurt. Surprisingly, it slid in effortlessly and with no pain at all. After waiting 2 days, it didn't hurt for 6-4, but it hurt a LOT from 8-6. Is something wrong?