i had back surgery and have been on percocet. my dr put me on fentanyl patch 50mg a few weeks ago. yesterday night i started having really bad anxiety and i realized that i was supposed to change my patch and hadnt yet- ive been changing it around 2pm and the anxiety started around 9pm. when i realized it, i immediately put the new patch on. could the anxiety have been from withdrawal? can withdrawal start that quickly? can you have withdrawal after only being on the patch for a month?