Totally understand your hesitancy to go back over possibly nothing. But my dr told me once that most doctors would prefer to see a child and it be nothing, than to not see them and it be something. At the very least I'd be calling your normal doc and explaining the situation and asking to get in urgently. Failing that I'd take him to hospital (is there a different one you could go to if you're worried about showing up again?). Just keep telling them that something isn't right.