DS started nursery and (surprise, surpise) got sick immediately

[bumpyandfrumpy]

After 1 week of nursery, DS (18 months) caught a very nasty tummy bug. I think the last normal meal he had was Friday night. Saturday-Monday he vomited and ate nothing just a few sips of water here and there. Since then he has had AWFUL diarrhea and has had two-three mouthfuls of food here and there.
My question is...at what point do I take him to the dr? I would have thought that he'd have at least a bit of appetite by now and that he'd be a bit better. He has lost loads of weight and is now getting a full-on cold from being run down.
I know it's viral as Dh got it on MOnday and I had it mildly too, but surely this should be improving by now?

bump

DD caught her first tummy bug at the same age and it dragged on nearly two weeks. God, it was grim.

The advice was that we should feed her as normal and not worry as long as she kept food and fluids down for at least 15 mins.

I do avoid offering milk, but that is not current medical advice - just from personal experience.

If you are worried that he is dehydrated then I would phone your GP, otherwise just keep up with the fluids.

Nowadays, when she catches tummy bugs, they last the usual 12-24 hours.

I would agree re dehydration being the main concern.

Do you have the rehydration sachets? DD had a sickness bug at about the same age and I was advised that first thing to do was to give her just 5ml in a syringe every 5-10 mins. If your DS is not being sick you could probably give more in one go.

Nursery bugs are awful for the first few months (conjunctivitis, tummy upsets, colds...) but they do seem to get better as their immune systems improve.

Thanks, all. He is drinking so am not worried about dehydration now (did take him at wknd as he couldn't keep any fluids down.)
Just can't believe how long this is going on. I'm going mad!