Are There Any Side Effects Of Using Fentynl Patches?

Hi I am 61yrs of age with coronary heart desease having three stents also I had neck surgery with a plate from c2toc7 I have been on Fentynl patches 75m since plus other meds thats about 1yr ago I was told to change the patch every 3 days but it was not lasting three days so They said go to2 days I can tell when its running out I become very very tired and cannot be bothered doing anything so I put a patch on and sleep when I wake I feel good and it goes round and round every 2 days same routine am I addicted when they are working I feel good no side effects but when it runs out I feel crap again I can,t afford the answer sorry