Rash!

Last night, Eirik's back inflamed out of nowhere really.  I tried taking pics but they didn't come out too well.  Its a flat rash and it VERY dry.  It spread quickly too and is bright red.  It might just be eczema? Aodh?n has seasonal eczema just like myself, so maybe that is all this is for Eir?k.  But it came on awfully sudden.  He has had egg yolks for the first time yesterday and Wednesday.  Could it be a reaction?  I just freaked out with how fast it came on.  Also, he is teething something FIERCE!  Fever, fussiness, lots of pain, etc.  I'm just watching him like a hawk today...it looks a bit better but I still am keeping a good eye on it.  Any ideas maybe?  I will try to get a good pic if I can.  WDYT?