Progressing backwards

Hello again! So I just finished week 2, and today was the absolute hardest day so far. I did pure cardio and cardio abs, I have now done pure cardio 3 times, and today it was so terrible. I was so insanely winded and had to keep stopping so I wouldn’t throw up. Nothing has changed, I’m eating the same, hydrated, not sick, etc.. But I feel like every time I do a video it just gets harder and I’m not sure why. I haven’t had to take breaks before but this week I’ve been having to take them. Y’all have any ideas as to why this could be?