I'm a 20 yo nanny... HELP

So I'm a 20 yo nanny with an 8 month old. I watch 3 little girls one with cystic fibrosis (CF). We live in AZ. The girl with CF has to go to the Mayo Clinic in Minnesota for testing for 4 days and she's asked me to come along to help with everything. All paid expenses and I can bring my son along. She's a newly single mom and needs all the help she can get. Is it crazy for us to come with? She said to give her a price and she'll pay me. We could really use the money. I just don't know if it's a good idea to travel that far with my son. And my husband works full time and can't watch him.