Anxiety during pregnancy

I have always had some anxiety but starting a couple of weeks ago (around 25 weeks) it got really bad and out of control really fast. Now it's difficult for me to even function some days and one time it turned into a panic attack. My doc put me on an SSRI but today it started up again at 4am and has continued all day in waves. It doesn't seem related to any specific stressor, it just comes and goes suddenly and unpredictably. Anyone else had debilitating anxiety during pregnancy who didn't suffer much from it before? If so did it go away after pregnancy? Any tips for dealing with it? I hope this doesn't continue after I have the baby. :/