Little ones become big ones in a blink of a eye, like I said before please keep a close eye on this chin, feed it at least 60ml of CC a day broken up into 3-4 feedings, make sure water is being consumed and give the chin the antibiotics when prescribed for the time they were prescribed, if you see and change in the condition for the worse such as heaving chest, lethargy, yellow goo from the mouth, weeping eyes, loose watery poo, sunken appearance of the skin call the vet back ASAP and advise.