Unfortunately, I don't think the antibiotics will solve your hen's problem. If she has EYP, the egg mass is in her abdomen and her body will identify it as a foreign body and attack it with white blood cells. Antibiotics will supress this but once you stop giving it to her, the infection will resume. I just lost a hen last Friday in surgery for a blocked oviduct. In her case, a partial egg shell had blocked her oviduct and yolks started backing up. Since the yolks were in her reproductive tract, the vet said she did not have an infection, just a distended oviduct that was pushing on her other organs. She survived the surgery but never came out from under the anesthesia. The vet told me her problem was like EYP, except not as immediately serious since the yolks were where they were supposed to be (sort of). She said EYP was much more serious and said surgery to remove the egg mass was the only recourse.
That is one vet's opinion, perhaps yours has a different take. I hope your hen recovers.
That is one vet's opinion, perhaps yours has a different take. I hope your hen recovers.