I've gone in sick but later I've found my T had health problems of her own so she could get ill/die if she got sick. She had to go out of town for months at a time in the winter, apparently had some illness like your 5 year old only it weakened her to the extent that she couldn't get sick like that again so had to avoid illness if she could; but she was in her late-60's/early-70's.

If you're not coughing, etc. and feel better "up" than you would resting, I'd maybe go in. If you're really tired and achey though, I'd get another hour's sleep or something.