How Long Does Fever Take To Resolve While On Medication?

Question: My dad went into the hospital on July 12th. He was taken going into septic shock from the UTI (we found out eventually) we got him in time, so he didn't have to go to the ICU, but was on IV antibiotics until yesterday. They found out what strain he had and sent him home with oral antibiotics (2 kinds) for 14 days. His fever continues to spike if he is not on tylenol. The nurse said if the fever persists to call the doctor. I assumed persists mean it wouldn't respond to tylenol, but it does. He has had chills when his temp goes up, but once he gets tylenol he feels better. My question is, will his fever continue to do this? At what point would we consider taking him back to the hosptial. They had originally decided to send him hom with a PICC line and do IV antibiotics at home. He is 80 years old, but in otherwise extremely good health, still drives, lives alone etc. They said his fever going up and down is to be expected for a bit. He was having such mental depression being in the hospital that I don't want to take him back if we can help it. They doctor looked for some time to find antibiotics that would help him. I'm just concerned that his temp keeps spiking. This morning it went up to 101.2, but came down after giving him tylenol. He was doing that some in the hospital too.

Thank you so much, that relieves my mind. My dad lives in a small community and though he got excellent care, the hospital isn't a big medical center.

The fever was controlled in the hospital but would spike some. It was lower there I think because he was on intravenous antibiotics and IV fluids, is that right? I know they were giving him tylenol there intermittently too, if the fever went over a certain level.

I know he had a very very bad infection and it won't resolve overnight. I just was concerned about the temp spiking. I have my own medical issues (Primary Biliary Cirrhosis and Thyroid Cancer) and I am having trouble with my stress levels and getting sick myself over this. Thankfully my older sister is taking care of him at home right now until he gets better and into the routine of taking his meds on time, etc.

Just a follow up on adequate hydration. Normal person should drink 64 ounces of water a day. Should he have more than that?
Thank you