Use this trick that works with diazepam. Methadone will be technically n your system in a week. If you ache, play the long half life game. Let your body know that it is still technically wearing off. Ride that wave mentally. The placebo effect can keep you pain free for longer. Same with diazepam. I am not at liberty to explain that, but that stuff is in your body after you stop. So let your mind ride the wave out, you follow me?
I am not pushing cannabis, but there are many different strains. I have had stuff that was one hit quit, that made me slightly anxious, but for instance, I had dispensary medicinal weed that got you going, but it was a primarily indica plant. Very relaxing. There have been leaps and bounds in cannabis extracts and strains.
Don't give up on a plant that has so many benefits. I respect your wishes of course, but they have a strain called Green Crack. It is like a pure sativa. You may not like that. Easier to get paranoid. That have indica strains that will knock you on your ass. They are heavy relaxing strains. Don't make a big deal or focus on it either. I can't imagine a small puff of herb just makes you paranoid. If ou sit there and think about the effects the entire time you are coming up, well you may be paranoid.
Spend five minutes learning the different types of strains. A glass tobacco use only

"tobacco pipe. is perfect for taking the tiniest ht you want. Don't muff out, but take one small controlled puff will reintroduce cannabis to you safely.
I am pushing it, because he right strain can make you pain free, mellow and jello feeling. Just forget what you knew and consider trying it.
It is too bad they don't use ketamine for pain over there. That will actually dial our pain receptors back over time. I know all of this from personal experience.
Oh yeah, benzos and opiates kill people. We can handle our shit, but other people will mix the two and die from breathing issues or what have you. Unless necessary, your better off without them. This thread is on now, so others should weigh in.
Honestly, the I have a pain, take a Percocet (US) 5/325, 5 mg Oxycodone / 325 APAP, works short term or breakthrough pain. They can be a bitch withdrawing.
Your doctor can do much better on opiates/opioids.
You are UK right?