What helps me when out in public is taking with me something from home that comforts me. For example I have a small bead pillow (its one of thiose cented eye bead pillows you find in the bath and shower sections and stores for relieving headaches and stress.) My past therapist SKR gave it to me. I take that thing everywhere with me. its always in my backpack. that way when I am out in public and start having a heard time I go to the bathroom and take a few minutes in the stall feeling and holding it and reconnecting with being calm and mentally aware of my surroundings in other words grounding myself. Other times when I know I don't have time to "escape to the nearest bath room I slip my hand into my backpack alone or under the disguise of locating a pen or pencil and so on and take a few quick seconds to hold the bead pillow inside the back pack.