For me, it was and continues to be the damn benzos. I was an opiate addict for probably 10 years of my life, and quitting them has only ever lead to short term discomfort for me (measured in weeks or a month). From the beginning of 2015 to the end of 2016 i threw in benzos into my daily mix, together with opiates. Really bad idea, but hindsight is 20/20. I went through drug dependency treatment at the end of 2016 and cleaned up, and have been clean since. The benzos still haunt me to this day. PAWS is real, and I still get flashes of it.
Imagine you're having a carefree day, things are going your way, and you're feeling pretty good about life. Suddenly you get cramps in your legs, your eyes begin to water, your nose starts running, you yawn to the point where you feel like you might dislocate your jaw, you can feel your heart beating in your throat, you get inexplicable nausea, your gut starts churning, everything starts to taste weird, your skin feels sticky, and you can't focus on anything. Feeling like a freshly made dopefiend all over. Completely out of the blue. And it goes away as quickly as it came. It's gotten milder and milder and more infrequent for me as time goes on. Now, being a seasoned addict, I know exactly what will help me feel better in the moment, but I know that taking it will perpetuate the symptoms. My body is still calling out for this drug, over two years after discontinuation.