I'm surprised it took this long for you to build up a tolerance to your medication! Consider yourself lucky in that regard. Don't worry too much, it's happened to me, and continues to to this day. I was on the patch also, and when I became tolerant,the dosage was rasied (in your case a 150mcg. patch should do it). When the dosage gets to high, a switch to a different opiod is warranted, and around you go!!! Good luck.
Your body has probably built up a tolerance. It happens after you have been on a medication for a long period of time. You will need to let your dr know so that he can make adjustments to your medication. Hope you get to feeling better soon.
Ginger