How do I know if my chicken is bad?

I almost always make grilled cajun chicken on sundays and meal prep it for the work week. Usually by Friday it's still good. But this time, I opened the chicken at work on Wednesday and it smelled weird. Not bad, but unfamiliar. It almost smelled like teriyaki chicken instead of the cajun chicken it is. I dumped it because it was offputting. Was it bad?