That is much too cold for breeding lows. In order for the snake to digest it's food properly it is probably going to need an area above 85F. There is no need to have a day/night change unless its unavoidable.
Snakes don't have a diaphragm. They are unable to sneeze. Most likely she was hissing at you, which is often similar looking to a sneeze.
Keep an eye out for an RI if your worried, wheezing sounds when breathing, bubbles of mucous, ect.