So sorry to hear you're feeling really ill. It is fairly normal, at least in my experience – though luckily I've only had real 'flu once (been careful to get the jab every year since). It kept me confined to bed for two weeks, and because it also induced a bit of a crash, I was off work for a good bit longer than that. Some 'flu symptoms are very like ME symptoms, and it was hard to tell when the immune response to the virus morphed into an ME flare. I did recover completely, though, and hopefully you will too.
Meantime – rest, fluids, paracetamol, more rest, and being kind to yourself.