Rex has been vomiting all morning (3 times!) and has bad diarrhea.... He did not want to eat breakfast today and I haven't changed anything in his diet recently. His stomach is empty he keeps throwing up water and mucus.... I tried feeding him by hand so he can at least get something in his stomach but he really doesnt want to.

Can this be some kind of virus? or is he just sick and itll pass ? could the heat be a part of it? it is very hot and humid today!

I would say a virus or something hes eaten.Dont give him any food for 24 hours-his digestive system needs to rest and you will just prolong the diarhhoea . just let him rest,encourage him to drink only.
After 24 hours or so give him a small meal of really bland food-like chicken and rice or pasta and see how he is. If the vomiting and diarhhoea stop he should be fine to gradually increase his food over the next 48 hours back to what he normally eats.
If the vomiting and diarhhoea continues more than today-probably a vet visit would be advised but Im sure its probably one of these quick bugs-and the heat wont be helping-Im assuming youve had had him somewhere cool all day?.
Poor lad-hope hes better soon-its heartbreaking when our babies are ill. xx

not eating isnt a problem but make sure he is drinking water, heat is a possibilty, mine isnt too good when he gets hot. hopefully he will be ok in a day but as mentioned already if he doesent pick up might be worth having him checked over at the vets! in my experiance though they are usually fine by the next day.

Hope hes is Ok soon.

hope he is well soon, keep him out of the sun and somwhere cool. xx

Rex is back to being a little brat this morning. He looks fine! A bit of diarrhea but no vomiting and is eating :) I tried giving him rice but he doesnt want to touch it so ended up giving him his kibble.

hi glad rex is ok again my puppy the same without the runs cant even get her to drink water at the mo if no joy later will syringe a bit down her she at vets tmoz for her second jab so fingers crossed think it some old food she ate at my daughters

Glad to see Rex is back to normal.