A white light moving very erratically.

I noticed a white light in the dark but clear sky. At first I thought it was a plane until I noticed the strange moving patterns. It was moving in a straight line when it suddenly appeared to drop down lower in the sky very quickly. Then it suddenly and quickly rose up higher than where it started. It even moved backward very quickly at one point and then assumed it’s original direction. These odd movements continued until it was out of my range of vision. I have never seen movement like this before. I am sorry I didn’t have my phone with me to record it. I am a retired high school science teacher who never expected to see something I cannot explain. I was outside with my dog when I saw this object.