Hi Anne-Marie, I moved your post to the General Messageboard so more people would see it.
I don't have this problem, but I know it seems to be quite common, particularly in younger people (I'm 51 so most of you are younger than me!). I think that the problem can be that you get a high then overcorrect so you end up dropping too low, then you might over -treat the low - a real rollercoaster that it can be difficult to escape from. It might be worth having some very boring, simple meals for a few days to see if you can get your levels to settle.