Babysitting dilemma - am I overreacting?

I babysit a first grader before and after school for $50 a week. I also watch her during school breaks, snow days, holidays, etc for a little extra money.

I have been having issues with her parents bringing her to my house when she’s sick. Before I started watching her I asked her mom what she expected of me if her child was sick. She said she’d stay home with her if she was too sick to go to school and that she wouldn’t send her to me unless she’s well enough to go.

Two incidents have happened since December.

In December on a Thursday afternoon she texted me that dad was picking the child up because she threw up at school. She texted me later that night stating that the child had been nonstop vomiting all night and had uncontrollable diarrhea. The next morning she texted me saying “she slept in and feels great so I’m taking her to school” I was honestly floored. Mom was going to be home anyway but she chose to send her to school because there was a school event going on and she didn’t want her to “miss out.” Well, that was also the week before my daughter’s birthday and I had told her I didn’t want risk my daughter being sick on her birthday. Well, she sent her to school and then her child rode the bus home (sits with my children -assigned by bus driver) and naturally on my child’s birthday she woke up at 4am puking her brains out. Then my other two children got sick and so did my husband. Her child continued to have explosive diarrhea for 5 days and she kept sending her to my house making excuses. I made it clear that I was pissed.

Most recent incident happened this week. On Friday she texted to say that she would have her son get the child off the bus because she, herself, had a fever and body aches. Well, naturally her child caught it. She sent her to me yesterday morning with a runny nose, looking sick in the eyes and a horrendous cough. Yesterday afternoon she got off the bus looking worse and I took her temp (100.6) and texted mom telling her. She sent the teenage son to get her and about 10 min later said he took the child’s temp under the arm and it was 97.5...well, he’s 14, it’s and under the arm thermometer (I have a temporal scanner) and honestly, I don’t believe her. I expected them to keep their child home for the day today but of course they brought her here. Took her temp when she got here (99.8) and about 20 min later it was 99.0 so yeah, they clearly gave her meds to reduce her fever. I told her I didn’t want her sick as we leave for a trip in a week but once again she chose to bring her sick child to me and be dishonest about it.

I’m getting pretty pissed off and I’m even considering telling them to find a different sitter after my trip. I know my kids are being exposed to things at school but my issue is that she’s blatantly bringing her here sick and trying to hide it by giving her meds and making excuses. She also called off work when SHE was sick but I’d sending her poor sick kiddo to school.

What would you do? Am I overreacting?