Had a pre-prepared Couscous veggie salad (Waitrose) for lunch at weekend. It was already use by 3rd August and tasted fine first time. I left it in fridge for 2-3 days and ate it on Saturday and was as sick as a dog in the evening. Hadn't eaten anything else bad and have done 2 x Covid tests since.
I feel better now - was on nothing/water and plain toast/crackers etc and eggs for some of yesterday.
I still have a nasty headache though, is this dehydration?