I felt rough a few weeks ago but because it was all feeling nauseous/bad tummy and no cough/flu symptoms I never tested until days into it. Bang, positive (albeit very faint by then), had no idea. Interestingly, my toddler then got conjunctivitis too, which would also fit with what people have been saying.
In the early days of Covid it felt like you knew what you were getting a bit, so everyone was looking for coughs and fevers, now it's all over the shop. I got what felt like a horrific stomach bug, my wife got a sore throat and fatigue, my three year old got a brief fever, cough and then conjunctivitis afterwards. How can you even tell?