Bad reaction to St. John's Wort

I used it for the past three days but it seemed to make everything much worse including anxiety.

According to wikipedia Hypericin is _believed_ to also act as an antibiotic, sounds a little far fetched but could it cause a herx?

If you're on certain abx it hinders the absorption substantially. It will state it in the detail you receive from the pharmacy and you can check online at web MD or any of the other reputable sites.