Hello and welcome! Some patients can respond *very* quickly to anti-thyroid drugs like PTU, so I would suggest contacting your doctor’s office to get a new set of labs (TSH, Free T4, T3) ASAP. It could just be that your body is adjusting to the change in levels, but since your fatigue is so significant, further testing would help put your mind at ease.
Since you are heading out for vacation tomorrow, you might check with both your endo and your primary care doc just to make sure you get a quick response. Hopefully, one of them would be willing to give you a lab order today and then call you with the results.
Take care – I hope you can get some relief and enjoy your vacation!