I don't think probiotics are strong enough to cause an Herxheimer Reaction. I took the highest dosage without prescription, in the billions, and didn't get anything but good bowel movements.
I know you get herx from detoxing taking Iodine, and its terrible as I'm currently experiencing.
I think the antiboitics killed your friendly gut bacteria, which are responsible for serotonin production in your belly, and that undoubtedly leads to depression, panic, and anxiety. You may need higher dosages of probiotics, or serotonin supplements like tryptophan or 5 htp.