a few years ago i remember having the same thing . i was so sore could hardley walk . i had to bend over when i did. i went to the er. i also had a ultra sound . but they could not see anything. then they descided to take out my appendit even thought that was not the problem. the doc said atleast we will be able to see whats going on in there.after my op. they said it was a large cycts on my ovarie that had burst and my stomach was full of blood for it and thats the reason the ultra sound could not find it. if u r still in so much pain go back to the er or doctor.
Clearly you have pelvic inflammatory disease. In some cases, oral antibiotics are not enough; IV antibiotics may be needed. Or, even if no abscess was seen on pelvic ultrasound 4 days ago, one could have developed in the meantime. Return to your provider right away. Delayed cure risks infertility, so don't sit on this problem (pun intended).