I Recently Went For A Walk Outside And Ate Some

I recently went for a walk outside and ate some ice cream (really hot day). I then entered a building that was air conditioned. I was looking at a person while talking to them fairly intently and when I turned away from them my vision became almost static like and my right ear popped like on an airplane. I then sat down (feeling a bit nauseous after walking and eating ice cream (which happens to me every time i eat and walk)) and it passed after like 4 minutes. As I walked back home, the back sides of my head hurt a bit. I'm worried because of the sudden vision change that it might be something serious.