Miserable 2 1/2 year old 🥵

Looking for some reassurance here.. my 2 1/2 year old son has been such a miserable child lately and he’s making me miserable in the process.. My oldest 2 never went through any terrible 2s or bratty phases so I’m completely lost.. my son speaks in full sentences so I know nothing is actually “wrong” but he just walks around crying and whining and talking back about every little thing allllllll day and it’s driving me crazy. When he’s not in this evil mood he’s the sweetest happiest boy but there’s no in between.. He just got his last four molars in and they’re all finally fully in as of this week so I was thinking maybe that could explain this.. or idk if this is just terrible 2s.. someone please tell me this will pass before I go nuts 😩