The wheat affects me very slowly. It's not like I eat bread and the next hour I'm in pain or on the toilet. It's more that my health slowly deteriorates when I eat it. And I don't have to eat much, a slice of bread a day suffices to get my health going bad. I get inflammation, feel tired, I feel cranky, my body starts to hurt. After I stop it, it can take 6 weeks for all the symptoms to go away!
Because the effect is not immediate, it took me some time to figure out that it was really the wheat that was causing this subset of symptoms. I started and stopped a few times. Last time I did eat it, I ate a lot of it in the form of wasa crackers one day, next day I really felt it. So now I'm sure of it: it's poison for me.
I hope for you that your back pain is a healing crisis, I think it is. But it can take some time to heal, especially if the damage was substantial! Good luck!