Dear Prof

Unfortunately my optimism was short lived and being back at school has caused my almost 4 yr old to have a severe nasal drip together with the coughing. After almost 4 months of being healthy, he is absolutely back to square one. He has lost his appetite and is blueish under his eyes. But having said that, his brother, almost 2 (in March) who have now started going to school has the same symptoms, almost worse (except for the blue eyes).
Their noses are not infected yet, I just spray it with saline twice a day. The pharmacist recommended dimetapp for both kids. I gave it to them, but I just want to make sure about the age thing, because the bottle says not for under 2 yr olds, although the pharmacist said it was fine.
This, I started on Monday.
Yesterday the little one had a bad allergic reaction to something at school. He had a nap and when he woke up, his cheek was swollen with red and whitish bumps. They wanted to give him allergex, but I said no and then the put on some anthisan, which helped, because by the time we got there it was already cleared up. I''m not sure what caused the allergy. Nothing they mentioned seemed suspicious. But what I wanted to know is, should I send allecet or celestimine to school for such cases and because he drank some of the dimetapp the previous night, could he take anything at all?
Also, does it sound like a food allergy or maybe a reaction to a bite (I didnt see anything), or what should we be looking out for?

Thanks a lot