I'm sorry you're in pain. I know how hard it is to keep going.
I started Enbrel at the first of the year and was doing pretty well with it until I had a sinus infection in May. I skipped one Enbrel shot and one dose of Mtx and went into a pretty bad flare. I saw my rheumy at the beginning of June and we decided that I should stay on prednisone for another month and see if the Enbrel started working again. I'm finally down to 5 mg/day of prednisone and feeling like maybe the Enbrel/mtx combo is doing its job.
My experience is a little different than yours, but there aren't really any answers set in stone when it comes to RA. It's always "wait and see" and "maybe". Try to be patient and let the Enbrel do its job. My rheumy said in her experience, if it worked before, it will "probably" start working again.
I hope you feel better soon. Keep us updated; we worry!