When Alex gets quiet, I know he is usually sick. This was the case yesterday (what also tipped me off was the projectile vomit).
I knew he was better today (albeit tired) because he was whining about every little thing. Case in point: I left the room to go into the next room and Alex let out a scream that would pierce every eardrum in the block. Running after me, he shrieked, "Don't ever leave little boys alone!" When I told him it's a small house, and I'm always within earshot, and he is quite safe, he responded with, "Well there's a texta out there with the lid off and it's going to DRY OUT if you don't come back in,. QUICKLY!" And we're back.