My father, who has advanced Parkinson's disease and in his eighties, has fallen and struck his head. What do I look for?

I would call 911. Explain the situation. He could have any number of injuries that could be life threatening. Bleeding in the brain may not be immediately apparent and can be fatal.

I agree with @gorillapaws that you should call either 911 or your local hospital.

The ER in my hometown urged people to come to them in case of emergency (apparently many people think now that the hospitals are total no-go areas now), because they’re still up to their ER tasks.
They specifically mentioned symptoms like those of heart issues, but not excluding others.
I would just call.

I would seek medical attention at the ER.

I know several people who died because of hitting their heads and not seeking attention. If they had, and had gotten a CAT scan (showing they had bleeding on the brain), they might be alive today. One actually went to the doctor who should have sent her to the ER but he didn’t, and days later she felt ill and ended up dead.

This is not something you could diagnose yourself.

Sometimes the fall wasn’t just a fall, but caused by something else. A broken hip, a mini stroke. I agree that a call to the ER is your best bet.

So, how’s your dad? Please let us know when you can.

Call 911. Ask for EMS. The EMTs, can do an on site evaluation. Then. They will be able to advise you further…

I’m so sorry this happened to him—and to you and to your mother. He’s fortunate to have you looking after him. I don’t know anything that would help you, but I do send good wishes.

I would do what the other have said call and seek their advice, just wondering is your father also suffering from cancer as well, because I have never heard of chemotherapy for Parkinsons.
And yes being on Chemo would have his immune system very low.