I'm exhausted and don't know what to do.

I'm 22, male, and I finished C25K a fortnight ago. Since then I did 3x6k and 3x7k, my last time being 36 mins for 7k.

Now, the problem I'm having is last session while I felt like I could have ran 10k, my legs were so knackered and now today, my rest day I did light bodyweight and I've got ZERO energy.

I'm worried I'm not going to recover enough tomorrow for my 7.5k run.

I'm a novice runner. Was I meant to take time off? If so, how do I do it without serious regression?

Or can I power through and complete my goal of running 3x10k? Adding .5k a week.

Or perhaps I should do some tapered build up running. For example 1x6k, 1x7k, 1x8k in a week?