Hi @unicorn44 You sound absolutely miserable with the side effects resulting from levofloxacin! That’s awful and I’m so sorry that happened to you. The hives and allergic responses do sound similar to what other members report with mast cell activation syndrome.

Mast cells act as first responders in our body help protect our bodies body from infection. But they can also be triggered by allergens or what they perceive as a threat to the body. When triggered, mast cells release chemicals that cause symptoms such as hives as the most obvious. But here are other side effects as well.

To help you understand a little more about Mast Cell Activation Syndrome, here are several articles to act as a primer for you. They may give you ideas of where to seek help and also what questions to ask.

~From Mayo Clinic: https://www.mayoclinic.org/diseases-conditions/systemic-mastocytosis/symptoms-causes/syc-20352859

~From Cleveland Clinic: https://my.clevelandclinic.org/health/diseases/mast-cell-activation-syndrome

An article I found from EDS Clinic really presented the information well. I don’t know anything about this clinic, but their information correlates with other credible sources to give an overall explanation for Mast Cell Activation and types of treatments.
https://www.eds.clinic/articles/treatment-of-mast-cell-disease
If you haven’t already, I’d suggest seeing an allergist. This would fall under their expertise. There has been some help for people with MCAS using a dual approach of taking a 2nd generation H1 (histamine blocker) such as Claritin or Zyrtec in combination with an H2 (histamine blocker) such as Tagamet or Pepcid (yes, the antacid meds) Together they calm the system. But this should be done under the supervision of an allergist. From my understanding it can be trial and error to get the right dosages. But if it helps…it would be worth a try!
Have you seen an allergist?