For many years I was a single Mom (now happily remarried), and my youngest DD was chronically ill.
Thank goodness my boss, and company at the time were very understanding. I took sick time to take care of my girl quite a bit for a couple of years when she was at her worst. In my case it got hard to hide it from co workers. Most were sypathetic, but a couple were pretty nasty. Until I said I'd be glad to trade places with them if it meant my kid would be healthy, and they could try having a sick child. That shut them up quick.
Thankfully my current company doesn't have sick time, just paid time off for any reason, and you can call it in if there is a problem. A lot more companies are going that route.
Good luck and I hope your kids have speedy recoveries.