Help! Any suggestions for treating SEVERE anxiety during pregnancy?

I'm having really bad anxiety right now, I'm 16 weeks 5 days along and before I found out I was prego was on an anti anxiety medication but got off of it for the baby right when I found out. Now I'm having full on heart palpitations because of it and nothing I've tried is working. I've tried meditation, exercise, lemon balm extract.. pretty much everything my doctor has suggested but it's not really making any difference. I try to think positively but even the slightest stress causes the palpitations to start. Any advice/suggestions would be much appreciated! Also Zoloft is a no-go (I had a bad reaction to it last year). I'd like to take a natural route if at all possible.