Like Susie said, my PM & I agree on a drug holiday at least once a year (sometimes I get sick & end up on an unscheduled "holiday").
FIRST & FOREMOST: Please, please, please do NOT do anything without first consulting your PM. You may have an underlying health condition that could result in serious illness and/or death if not managed properly. Almost everyone can go on drug holidays, but some people need to be on a slower titration schedule to prevent dangerous health events.
For me -- and I have a very minor heart condition, so it may well be different for you-- when I am feeling better (i.e., in pain, but not as much as usual) then I work on slowly decreasing the number of doses I take per day (I'm on the lowest dose, so if you're on a higher dose, you would cut down the dose first, then the # of doses/day). I do this by setting specific times when I take my meds -- regardless of how much pain I'm in. Once I'm down to 1-2 doses/day, I apply a Catapres patch (off-label use of a bp med). The next day I stop all narc pain meds. We increase my doses of Lyrica, which makes me sleepy but makes the pain more bearable. I try to stay off the pain meds for at least 7 days. When I can, I stay off for 14 days, but I rarely make it that long. Then we slowly see how much medicine I need after the reset. Usually I need the same amount as before, but I've been on the same dose for nearly 7 years so something must be working (and physically I've gotten only a tiny bit worse -- if you have a rapidly worsening condition drug holidays won't work so don't put yourself through the misery).
During the holiday period, I drink lots & lots of water -- at least 3 liters/day. I wrap myself up tightly in sheets & blankets and if I have to go out I wear tight fitting clothes. I've found eating helps somewhat so if I really want more pain meds, I have something to eat. Basically, try to stay as warm as possible. If I can walk, I do, but sometimes the pain is too awful so I just rub my legs. Compression stockings are somewhat helpful if I am dumb enough to try going into work -- usually I get very little done, so don't schedule this during a peak time at work. For me, I am on an ultra-short acting med, so the withdrawals are much more intense, but they really only last for about 3 days & then start getting much better. Of course, then the pain starts up something awful.
If I need shots, my PM will see me. If things get really dreadful, we will sometimes try another narcotic pain med. There is research that shows that switching to another med in place of a drug holiday does have some benefit, but a true holiday is ideal. If all else fails, we go back on my normal med early.
Hope that helps. Good luck!
PS -- If you're thinking about the Namenda, I personally would talk to a neurologist about the possible side effects & long term effects of using that drug for an off-label use. Any drug that crosses the blood-brain barrier has a strong possibility of causing severe side effects. Maybe it would be worth it, but it seems like that it would be pretty risky to me.