Diflucan/fluconazole - is one of the Azole antifungals - this group of drugs has also been found to be active for bartonella - in fact much higher activity than all current anti-bartonella drugs like azithromycin.
see Zhang's study
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc6628006/even though bartonella is not thought to produce much by way of lipopolysaccharides that are traditionally thought to drive herxhiemer reactions - many people here with Bart of suspected Bart suffer significant herx like reactions from taking things that are active for bartonella - and its such a prominent symptom for those with bart - often debilitating herx like reactions even from mild treatment - that there must be an explanation to do with herx like effects.
the small study on fluconazole and lyme disease in people is interesting - but it is known that fluconazole is not active for borrelia in the test tube/ lab - so the mechanism of action remains mysterious.
were the people in that study with lyme that failed prior lyme antibiotics - but then responded to 25 days of fluconazole, actually co-infected with bartonella - that when treated with fluconazole this allowed a lot of them to recover - certainly possible as bart is a common co-infection and testing v poor.
or is the fluconazole acting on the white blood cells to make them more numerous and effective - there is a discussion of this white blood cell enhancing effect in the post on microbial survival in the spleen in common infections
https://www.healingwell.com/community/default.aspx?f=30&m=4275973or is fluconazole perhaps very active against biofilms - another important mechanism in chronic infection - perhaps the most important mechanism by which borrelia persist despite antimicrobial treatment - although i have not seen anything on this specifically for Borrelia - the fact that it seems so effective for stationary phase cultures of bartonella is perhaps a clue
the herx from bartonella seems perhaps the most likely to me - as the symptoms are also very much like bartonella - anxiety, panic, sleep disturbance, hot/cold, muscle twitching etc - these are very similar to those i get when treating bartonella. i also have lots of gut issues which i attribute largely to bartonella - as its known for this - and i think its possible that many people focus on candida when in fact bart may be the root cause
finally, in my opinion, its OK to take breaks from the abx for a few days or a week or so and allow your body to keep the herx like reactions within reasonable limits - but only as part of a longer overall strategy to treat infections while managing herx (in preference to a random few days of antibiotic here - or antifungal there if you see what i mean).
the concept being that overall treatment should be as part of a commitment to a long term plan with a clear strategy that includes coverage of all of the suspected pathogens involved in your case and also breaks and methods to manage inevitable fallout / herx effects from treatment.