Toddler has a fever 😳🥺😖need advice URGENT!

My daughter complained earlier about a stomachache and went to sleep.. i decided to take her temperature and it was 101.0.. but I’m worry because I have my new born she’s 6 weeks and I don’t want her to get sick😳🥺what can I do to prevent my new born from getting sick.. any mom me with experience give me advice?! Please