I get something like I have a cold for a day after, headache, tiredness, sneezing, runny nose. I get brain fog the same day too. I've not heard or read of this

I get something like I have a cold for a day after, headache, tiredness, sneezing, runny nose. I get brain fog the same day too. I've not heard or read of this occuring normally. It's not bad enough to stop me driving but it is enough to stop all work. I think it's fatigue basically and I've found that gradually increasing my fitness allows me to do more before this starts. But it's not listed as what fatigue is, especially the brain fog bit.