4 month old has fever?

I was just wanting to know how much a infants temp fluctuates and when? I already called the pediatrician because my 4 month old has a cold with conjunctivitis and I was told to watch out for a fever. I checked Tuesday and she had temp of 101 so I gave her infant Tylenol and checked her all night and it was down to 98.5. The throughout the next day my husband said when he checked it was about 99 throughout the day the when I got home and checked around 9 it was 100.6 so I have her Tylenol, It again back down to 98 this morning. NOw it’s back in the low 100. Is this normal fluctuation or is she vitally getting fevers. Her head never feels warm and she hasn’t changed her demeanor or anything. Have an appt tomorrow for doctors for vaccines but may not be doing it and just having check up.