I have bad flashbacks sometimes, too. Mine are particularly bad with smells and sounds. Yuck, that's all I can ever say about them. I'm sorry you're struggling with such vivid ones.

I do encourage you to tell your T what's going on, so she has an accurate picture of how you are doing. Remember that you get to choose how much to discuss. You can simply tell her you're having bad flashbacks. You are in control, you can decide whether or not to give details.