Worse on herbals?

Diagnosed with both hydrogen and methane SIBO. Currently on my fifth week of herbal antibiotics and have been getting progressively worse and worse not better throughout the weeks. I expected to see at least some sort of shift in the right direction however am experiencing the polar opposite. Doctor said that “die off” should only last up to a week, but it feels like I have been in die off since I started the treatment. Has anyone had a similar poor experience with herbals? Asked doctor to switch to a pharmaceutical antibiotics because this isn’t sitting right with me.