Sounds like you may have hit that deer in the “black hole”. Its happened to me twice over the years. Its the area of a deer above the lungs but below the spine. It contains no vitals just meat. Ull have blood for a lil while, possibly cuz u may have clipped one lung but then blood will peter out. I would go back with a trail dog if possible and start where u shot the deer. If no dog i would grid search where u lost blood.