Okay, I see where I got confused in regards to how long I was supposed to run. The runs this week really are 3, 5, 3, 5. It's the rest periods that are 90 seconds and about 2 1/2 minutes long.
After the run, I got light-headed and it got so bad that I felt like I was going to fall down. My experience with keto led me to believe I needed electrolytes, so I took a half teaspoon of Lite Salt and a half a teaspoon of Concentrace (which has a lot of magnesium in it), then sat down. And now I'm feeling a lot better. It makes me think I should probably take those minerals before I run, especially if I run a long time.
Today I went 5.5 km (3.4 miles) which I've only done once before (and I forgot to bring my water bottle, which mistake I won't make again).