I'm sorry to hear that! I'm a "scientific" sample of exactly one patient, and I'm not a medical professional of any type, so please keep that in mind. For my first 10 chemos, I had a Udenyca injection 24 hours after my 5-FU pump was disconnected. My white counts were well within normal levels--in fact, they were unusually robust--so my oncologist then discontinued the Udenyca. Anyway, I was told that any over-the-counter antihistamine (Claritin, Zyrtec, Allegra, etc.) would work to minimize bone pain after the injection. I was told to take the med a few hours before injection and continue it for a couple of days afterward. They said the mechanism for why this works isn't understood, but it's thought to suppress the body's immune response. That is, your body is complaining about the order to make white cells, so it protests with pain, and the med helps disrupt that pain response.

I actually stopped taking the generic Claritin after a few injections because I never had any bone pain, with or without it. (Again, sample of one patient.) So I'm a poor source for how to manage this. Have you talked to your oncologist and/or your palliative doctor about this? I did a super-speedy google search, and I'm sure you've looked online too. I spotted an MD Anderson post that narcotic painkillers may not be the most effective or useful treatment for cancer-related pain. Maybe there are other therapies to try. I would talk to my MD about acupuncture and massage, maybe a different type of pain medication. I saw that hot and cold therapy (ice packs, heating pads) might help. You mentioned Claritin; I wondered whether a different antihistamine might help. I've seen people on this board mention CBD-based products, and I plan to ask about those as well if/when I get to that point. I hope you feel better soon!