Major Invisalign problem! I accidentally wore tray 3 a week early then changed into tray 2 the following week without realizing

I recommend going back to tray 3 for a few days and then moving on to tray 4 and continuing on as your orthodontist recommends.

If you wore 3 then reversed to 2 you should be able to wear 3 for a week and then progress to 4 safely.  A new aligner stage usually feels tight for a couple of days and the seating improves then too.  You always have your personal dentist to check if unsure.