I feel guilty when I call in sick, but to be honest I always think and have learned it's best to have a day off when you feel ill than trying to struggle on, because you make yourself worse and then need more time off.
What about collecting little man a bit early from nursey, that's what I do with rich, he didn't notice it was early, but you do get to spend sometime with him if you feeling better
Hope the bug passes soon, but don't feel guilty although I do xx