Needs admit. Torsion, ruptured cyst, appy, ectopic, chole, obstruction
All are possibilities.
Fever with nausea and vomiting - argues for appy or gallbladder. CT should pick these up.
Ectopic is ruled out if pregnancy test neg.
Torsion is ruled out with pelvic ultrasound.
Ovarian cyst ruptured. This is actually what I think is happening, just because it is the most common. Mostly self limited, takes 1-2 weeks for the pain to go away.