Bbt rise at 10dpo..

I had a pretty significant rise today making my chart triphastic, I expected a decrease in temps since it's a couple days before AF. Anyone have an experience with 10dpo rise? It went from 98.5 at 9dpo to 99.1 10dpo. I have taken dollar store tests and I see lines, but afte the time frame. So I'm guessing evap.