Why do I suddenly feel much worse than usual?

A flare is what we call it when all of our symptoms seem to intensify, so that we find ourselves in more pain, and functioning at a much lower level that usual. Flares can be brought on by stress, either physical or emotional, changes in weather, over-exertion, etc. Try to pace yourself and avoid intense periods of activity. When a flare hits, don't push yourself. Your body is telling you that it needs a time-out.