My father can't urinate, or defecate, and won't eat. What do I do?

As a nurse, I've seen patients who can't pass their urine in AGONY. Your father is going to be more and more uncomfortable until he's in horrible pain from not being able to urinate. This is a medical emergency!
Once the bladder has burst you risk peritonitis.
The body makes 30 milliliters of urine per hour even if you don't drink anything.

Go TODAY! He has too many problems to be second guessing what's what.
If they can't pass a catheter up the urethra (due to the prostate being very swollen) they can always put in a supra-pubic catheter.
He needs a scan to see if he has a bowel obstruction.
He needs IV fluids and nutrients.

This is not something to wait for. Tell him his life depends on this. GO NOW!

Does the doctor's service when you call say there is another doctor on call for him? Seems like there ought to be. Or can you call your dad's insurance's 24-hour nurse advice line? Worst case, I would take him into an urgent care clinic or ER. I'm not a nurse but not being able to urinate seems like a situation that needs to be addressed by a medical pro today.

Isn't it frustrating how these things always happen on the weekends?!! Richie, hope you can get some help asap for your dad.

Richie, I am sorry he does not want to go to the ER.. but frankly he needs to. His symptoms are not good, after 3 days.

Thank you all for your input, I really appreciate it — we did take him to the ER, and their first question, of course, "What is the main reason you brought him into the ER?" A very difficult question due to the combination of many symptoms to choose from; at that point including slurred speech, and seeing objects & people (that were not there). End result: A series of small strokes.
What I have learned: Take loved ones to the ER at the FIRST of any sign of ANY kind of abnormal behavior. The rest is damage control.

How long since he has had a bowel movement? I'd be worried about an impaction, which should never be treated by giving laxatives. The urinary retention could also be a medical emergency and will probably require a catheterization. He can go without food for a few days but if he can't even keep fluids down then that is strike three and I would not wait but get him in to see someone ASAP.

I guess you'll just have to make sure he gets in to see his doc tomorrow at the latest, hopefully it is easily treated. Push clear fluids and hold off on the solids unless he feels a desire to eat. And come back to let us know how it turns out.

I would take him to the hospital over his protests. You say he is not himself, he may well have a UTI or other infection.

The hospital can use a ultrasound on his bladder and determine if it is full. They can administer IV fluids to help with the dehydration. This sounds like a medical emergency, not a wait and see the doc he likes situation.

You couldn’t force him to go to be evaluated and did the best you could. Seniors can be so stubborn!
I bet next time you’ll insist he goes to the ER & hopefully your dad learned a lesson and won’t argue with you.
I hope your father is feeling better soon. 

Does he become physically ill when he tries to eat? Have you tried clear broths or things like Boost for him where he wouldn’t have to physically chew? Miralax works wonders for constipation, usually overnight and it’s not a drug. It must be safe, y daughter’s pediatrician recommended it for her 6 year old. Good luck and keep us updated.

Richie, I would gather up Dad and drive him to the nearest urgent care center. You don't want your Dad to be dehydrated as that can cause numerous problems, like confusion. And if there is a stomach or intestine blockage, it needs immediate attention like RIGHT NOW.

If Dad feels bloated, he will not eat as it is too uncomfortable. Something is going on with his stomach/intestines. Did Dad have Ensures before without any problems, or is this his first time? If first time, Ensures contains Corn-sourced maltodextrin which is a starch, which could do a tap dance on Dad's stomach.