Just as a starting point, my 2.5 year old has dysphagia and has to have thickened fluids. The thickener often upsets his tummy and he has mushy poop randomly. He also has airway malacia and GERD.
Last week he had watery diarrhea on Monday but he was finishing a weeks worth of antibiotics. It settled throughout the week but each day his poop was mushy. Then on Friday he randomly vomited. There's a bug going round nursery but he had been fine all day (eating etc) and was fine after, just a little warm (37.5). He had gulped down his drink whilst in the car and most of what he bought up was his drink.
He ate fine Saturday but by the evening he had a fever of 39.2. He had a normal poop. He had an awful night poor thing. On Sunday he was lethargic and just laid there watching TV. He even went for a 3 hours nap which is unusual for him. He normally has max 30 mins if any. He didn't poop that day but by the evening his farts were lethal!
Then yesterday he woke up with a rash all over his tummy which spread to his back, neck and face. It was like little pink/red dots. This then went to his face. The doctor said slapped cheek but it wasn't red enough for that and doesn't look like any of the pictures. He also had four loose stools yesterday which I am taking as diarrhea as it happened so often, even though it wasn't watery. Someone suggested Roseola to me but I've never heard of it.
Today the rash has gone down and is mostly on his face. His temp is normal. He's eating again and refusing to nap (so back to normal) but had a loose stool again.
I don't think it's a stomach bug as it was a long time between the vomiting and both cases of diarrhea. I don't know much about Roseola. Does anyone have any ideas? I'll attach pictures of the rash.
Also disclaimer, the GP has asked for a sample to check he hasn't got anything from the antibiotics. He is on prophylactic antibiotics so is on them regularly.