It is actually not that uncommon for babies to vomit when they have a cold. The mucous can drain into their stomach which is not a very nice feeling. This can make them lose their appetite and also throw up when they have something to eat (especially milk unfortunately!). It does pass as they get better. The best thing to do is lots of FESS and lots of tummy time to get the mucous to drain out the nose instead of down to the tummy.

Your DS might be having difficulty with chunky food today because he might have a sore throat. Think about how you feel when you have a cold - they feel the same except they don't know what's going on and get get a bit frightened.

If you feel your DS is dehydrated, def go back for a check up. But keep in mind that there is nothing they can do for a cold other than monitor him to make sure he doesn't dehydrate. Antibiotics don't work on colds. Your doctor may give you a prescription for something like Demazin which will help dry up his nose.

Hang in there - kids are really resilient and bounce back quickly.
HTH

MG