I deal with flashbacks in many different ways but they all boil down to self nurturing/taking care of myself/grounding...

take a bath, smell apples and cinnamon, breathing, yoga, ,meditation, weight lifting, spend some time looking at my children, having my wife hold me, listen to calming music, painting, writing, sewing, what ever happens to calm me down and ground me back in the present moment.

maybe you can read some of your past posts and that will give you an example of some things you like to do, things that are calming to you...

maybe you and your therapist can make a list of calming/grounding things for you to do..