Take her in to the doctor to make sure s/he doesn't have something like strep of an ear infection which needs antibiotics.
I'd let a low grade fever run. It's the bodies way of fighting off the crud. If it's causing her discomfort, try to find other ways of keeping her cool and if it's disturbing her sleep, give her just a touch of Tylenol about thirty minutes before she goes to bed. But make sure it's for infants and not children, and check with the doc for proper dose, since it goes by weight and not age.
Well your little one may just have a little bug. What you need to do is give him infant Tylenol and Ibuprofen alternated every two hours till the fever breaks then give either one of the meds every four hours till it stays gone. If it persists more than 48 hours or gets worse then get him to his doctor a.s.a.p. but you must not stop giving him the medicine even if his fever stops until it has stopped for several hours to a day. You may still want to follow up with your doctor even if he is better.