If you had significant dehydration, your pulse would be rapid, not slow. Same thing for anemia. I would be looking at drug side effects, hormone inbalance, or cardiac issues.
If you are feeling dizzy or lightheaded, you need to make an urgent care appointment, or go to the ER. If not, the blood pressure may be within normal limits for you. The numbers by themselves mean less than when compared to past values.
It is unclear to me why eating would cause breathing difficulties...
For me, 90/60 was my normal operating BP. It is how you feel that is most important. So urgent care may be where you need to be. Could be a panic attack...or something else. That's why evaluation may be in order.
Jan