Sore/Tight muscles after 1 week?

Hi guys! Don't know if this was asked before.

I'm returning to fb strong after about a month of cardio and yoga, I did an advanced core workout 6 days ago and my obliques are feeling weirdly tight even now, although I made sure to stretch them almost every day. I'm also feeling kind of dizzy/tired. Just finished my step class an hour ago and i had some difficulty during some exercises, something that didn't happen before.

I checked out my food intake and it amounts to 1500-1700 calories per day, and my only activities are either yoga, 30-40 minutes FB workouts or aerobic step classes. I had DOMS before, the maximum being after 48 hours.

I admit I'm guilty of not sleeping that well during the last couple of days, but could it impact my workouts and recovery rate so much?