Have you tried Grounding, Shielding or Cleansing your Energy right before you leave to go shopping or even while you are in the store, on your way, etc. ?
It can be as simple as rolling down the window & letting some fresh air hit your face, splashing water on your face, washing your hands, chewing a piece of gum or a mint, etc.
You might also find this odd, but do you have a place that makes you feel safe & very serene?
It could be a room in your home, your back porch, a beach, your backyard, a favorite place to eat, etc.
If you do, you might want to try this:
Take something from that place where you feel safe & at peace & carry it with you.
It could be a piece of the ground(dirt, earth, gravel cement, brick, limestone, etc.) You can place the loose dirt, etc. in a small baggie or tiny container & carry it in your pocket , a seashell, a coin, a dollar bill, a postage stamp, a stone, a book of matches, a napkin, a business card, a marble, etc.
If you haven't used the Empath Survival Program, you may want to take a look at it.
I hope you find relief soon,