I'm not even the one who got chemotherapy, and I think I had secondary chemo brain. So, I started the habit of writing everything down. There's just so much to think about that it's easy to completely forget about things. I also rounded up everything related to dad's health care and organized it into one location. He did have the cloudy mind too, and could not remember things.
I write everything that happens, and all future appointments onto a single calendar.
The best thing for dad's medications has been a cheap pill box with the little compartments similar to this http://www.walgreens.com/store/c/ezy-dose-one-day-at-a-time-weekly-medication-organizer-tray/ID=prod6145638-product We just fill it up once a week, and it's easy to see if he missed any. If he started missing something repeatedly, I set up a funny alarm reminder on the computer. A lot of people use the alarm on their mobile phones. Anything that doesn't fit into the box, like your injections, you can keep them in the same place.