Try not to worry too much. As I said in a previous reply my OH was admitted to hospital with a temperature of 37.7 and he had no other symptoms at all. He was admitted on Thursday and they kept him in until Monday, he was on intravenous antibiotics immediately, they can only give those in hospital. The main thing they are scared of is Sepsis, that can only be stopped by immediate treatment with antibiotics, it is easily missed by people and can be fatal within days if left untreated, the initial symptoms can easily be mistaken for flu so people tend to leave it or try to 'ride it out'.
Don't be scared if your dad is in an isolation room, my OH was (with his own bathroom!) It is just a precaution.
You did totally the right thing in ringing the hospital, it has allowed them to nip it in the bud when things can easily be rectified.
From the way the staff were with my other half it would appear to be quite a common occurrence with people on chemo.