Before I started tx a nurse told me head/neck is particularly hard for men. I asked why and I will paraphrase her answer:

Men are stupid.

We say things like "I have a high pain tolerance"
"I don't need a port. My veins are awesome"
"No, don't need help. I've got this."

I said every one of those. There comes a time (and it sounds like you're close) when you need to get through TODAY. Yesterday has obviously passed. Especially with radiation tomorrow is already on the way and will get here soon enough. So today: get your calories and fluids. If you're tired, rest. If you can't rest get meds that will help you rest. You must rest. Attitude is very important. Being down can turn in to a spiral and should not be trifled with. Everyone has bad days but the trick is recognizing it and responding to it. I always felt better when I was helping others, especially when I didn't really feel like helping anyone.