Don't worry for next week, relax and enjoy your flying week, let's hope the weather is with you!!
If you are happy with your current headset, try to borrow one from another student and see if it helps.
Go to bed early and relax, i myself i'm doing my PPL flying (if the weather allows it) every day and ofcorse it is very tiring!! My wife says the house is much calmer when i started this intensive PPL training.
I think the pain in the head is about the huge amount of concentration you need to use to perform the multiple flying items, step by step it will go automaticly, don't worry. You did got your medical already ? Don't worry then.
On what plane are you training ?