I know what you are talking about. It's like you are running on cheap batteries.
I climb for two days and I'm done, and not as hard climbing as last year.
"Everyone should have a plan for the zombie apocolipse" Courtney
Drink water, rest more, eat less fat and more protein. Drink energy drinks! Give enough time for your muscle fibers to regenerate. I had a break in climbing for 2 years (meaning was climing only twice a month for 2 years). It took a while to get back to where I was before.