I agree with Borderlyme - water temp and staying in the bath for 30 minutes the first time can easily be overdoing it - and when a person overdoes it with detox methods, it's causes a herx.
Next time try staying in the bath for only 10 or 15 minutes and build up the amount of time that you stay in the water. Since you are only staying in the water for a short time, you can also reduce the water temperature so that it doesn't help a herx along either.
The first time I took a detox bath, it caused such an increase in my symptoms, I was bed bound for 2 days! I was absolutely overloaded with toxins! It took me a while to build up the amount of time I stayed in a detox bath to 30 minutes, but as I said in my previous post, everyone is different. I also remember trying to use those foot pad detoxing thingies - those can be pretty potent too! I had a 3 day migraine from those the first time!
Just remember that if your body is in a healing crisis (a herx), it can't heal during that time. So take it slow and build up the amount of time that you spend in a detox bath.