Yes, this has happened to me, also. Waves of panic attacks coming at me with no trigger that I ever identified. I would call my T and he would reassure me I was OK - standard words:
Remember to breathe - Are you safe right now at this moment - Is there anything happening at this moment that will harm you. Somehow, those words, spoken with his compassionate and caring voice would carry me over the humps and bumps. Now that I am on Lexapro and Xanax they have stopped so I guess it was brain chemistry firing off. But it is critical to have a T and a pdoc to assist you with these type of frequent attacks.