Question about hospital re-admission

We took my son to urgent care in October and the physician that saw him suspected Pneumonia so they took and Xray which confirmed, and told us to go to the ER.

Son was seen at the ER on October 14th and admitted that day. They said he had RSV, but said their Xray(taken same day) did not show pneumonia. He was given IVs and Oxygen and was released two days later. (Had a 104.5 fever the day he was released.

Two days after release he didn’t seem to be getting better so we took him back and they admitted him after doing an X-ray and finding pneumonia (same hospital). He was given IV antibiotics and eventually released two days later.

My insurance covered the first visit entirely because they said he was suspected of Covid.

For the second visit my insurance was billed ~20k of which they negotiated down to 14 and I paid 20% of that which was around 2800. Do I have any recourse with the hospital as my son was re-admitted to the hospital two days after they released him? They gave pushback that he originally had pneumonia and the he was re-admitted for pnemonia. If he had stayed the entire time and they treated him for pneumonia, the visit would have been fully covered under the COVID insurance guidelines. Hoping for some advice if you have any.