I know others have mentioned this on the first injections but didn’t have the same pain since so maybe it’s just the shock to the system and will be better for future ones.
I’m on filgrastim injections and although the bone pain wasn’t as bad as you’ve described I had to take pain relief the first time as I could really feel it in the bottom of my spine and was worst when sat down. But I’ve not had any pain since that first time and have been on them a few weeks now. Hope this is reassuring .