You received protected oral sex, and when your penis touched her vagina, it was covered by a condom.
Chances that you got an STD are very low, but how did your penis touch her vagina? Was it a quick touch, a lot of rubbing, or something else?
HPV doesn't cause fevers, and it would take months before you had symptoms, if you ever did.
Syphilis symptoms don't show up for weeks, and wouldn't give you a fever.
HSV might give you a fever, but you'd also have blisters.
Those are the only STDs you'd be at risk for if there was a lot of rubbing, and any of your bare genital skin touched her genital skin for a long period of time. A quick touch won't transmit it.
If your fever lingers for longer than another day or two, see your doctor.