Sudden drop in function

Good morning all, I realise that this condition is progressive and that we are all different and yet the same but I wonder if anyone else seems to get a sudden decline.

i  chug along quite ok but then I can suddenly drop in physical and mental function. Fatigue can be massive for me and I do try to pace myself I do have a busy life I am still working just about but then some days I just seem so much worse.