chest cold? hives? pinkeye??

[hjpj]

My 2 year old son has had a nasty head cold for 3 days, it went through the whole family.  Congested, runny nose, low grade fever, coughing the whole shot.  The other night he ate spigetti for the first time and broke out into a rash on his belly and around his neck and chin.  Called the doc, gave the benedryll and watched him,  all good by morning.  Ok this is where it gets confusing.  The next day he develops nasty pink eye.  Then that night after vomiting his yogurt and butter and jelly sandwich (cough induced vomit), he gets the rash again.  It happened about the same time the night before and there stops the similarities.  This last nights rash was worse though, back, chest, ankles, wrists neck and cheeks.  Soaps havent changed, no new cloths, or meds.  Cant figure it out and am worried that if it happens again how bad will the rash be this time.  Oh it did go away again by morning with the benedryll.  Any idea's?