What Causes Dizziness And Warm Sensation In The Body?

I m an active, healthy 56 y.o. woman on no medications. Around 1:30, while riding my horse, I started to realize that I was thinking about some things and I didn t know if they were real or from a recent dream. Not dizzy. I dismounted. Hadn t eaten all day so had a piece of chicken, then a bunch of cookies and some cranberry juice. I feel warm, my heart rate (per fitbit) is 78-84. Hard to describe but a bit like being waterlogged, but in my head. I was with 2 people I ve known for a long time but couldn t think of their names. One said her horse s name and I didn t recognize it. I looked in my phone to get her name and what was shown there wasn t familiar to me- I swear it read Borsch (or something) and her name is Byars. I do have a bite behind one knee. Could this be spider-related? Freaking me out! Thx