My dad has Parkinson's, Sundowners and has contracted a bad UTI that's effected his thinking. He is in the hospital with fever. What's wrong?

My daddy is 95 and has had pd since he was about 74. He contracted a bad uti and it efected his thinking. Also he has deveoped sundowners. Up until two weeks ago, he was still walking with his walker, doing crosswords and answering questions on jeoparrdy. He has never been incontinent, and is was as sharp as a tack. He has lived with myself ( his doughter) and my husband for 8 years. Before then hw would live in Florida 6 months where he was still golfing, driving and living alone. He decided to hang up his keys and clubs at 90. He has been in the hospita for 2 weeks, and he keep spiking a fever from 99.5 to 101.1 Up and down. They can't seem to find the reason. Also, can you suggest a reasonably less mind altering drug for the sundowners, other than geodon, or seraquel? Thank you