Off topic...Fleas

I just found a flea on my daughters pj's when changing her!!!! I have had my dogs going on 13 years and 7 years and they have NEVER had fleas before. I just give them sentinel monthly and have never had an issue with fleas...I've never had to use anything else. What's the best to use with kids around? Any natural spray I can use around the house and on them??? TIA!!!