should i be worried about DS (20 weeks)

[ponytails]

we have all managed to get a cold in the house but my DS2 seems to have got it the worst. he is very snotty and is refusing to take his milk. since 7.30pm yesterday ive only managed to get 8oz of milk down him but added to the problem is that he also has very runny poo.
i took him to doctors this morning but they were not concerned. surely its not normal for a baby to drink so little

Are there wet nappies between feeds?
Baby alert (or alert as can be with cold)?
Can you use a baby saline spray for colds? Calpol do one.
My DD sometimes used to drink only 14oz in 24 which was not ideal but was OK in pediatrician's eyes.
Will your LO take a cup or spoon?

Sorry, should have said - worry when no urine, dry lips, lethargic. That said I am no medical professional so if you are worried go back to dr or to A&E.

I would try nose spray, Calpol, milk via spoon and a humidifier / DS in bathroom with shower running.