I am 71 years old. I was 67 when I began taking those same three antibiotics 3 times a week. After no improvement - I was increased to the same three antibiotics 7 days/week. I continued this regimen for about 4 years.
I began to think I was showing severe signs of dementia after having difficulty finding local area destinations I had known for 30 years. I even had trouble finding my way around Mayo after doing the same routine appointments three or four times a year for 4 years! In addition to confusion and temporary memory loss while on the antibiotics, I also had terrible mood swings and paranoia.
I shared all of this with my Mayo pulmonologist. Since my bacteria count was so low by 2018, it was believed I needed a break; I was put on a “med holiday” for one year. Yay!
During my year off the antibiotics, I realized I was able to find my way around town with no issues, and my “feeling lost” and “in a fog” while at Mayo was also gone. The mood swings, paranoia, and confusion were totally gone. I felt so much better mentally.
But here I am again a little over a year later, my lung health is not good again - and, I am going to find out tomorrow what the new plan is. I do know that my mental health will also be considered when choosing antibiotics. I am so glad and very thankful I have a pulmonologist I can trust. Don’t be afraid to ask questions and to share how your lung health treatment might be effecting your general health. Hoping thus helps a little. And - please tell stepmom’s pulmonologist what she is experiencing. Be Blessed.

I had similar effects but probably not as severe as your step-mother. Ultimately my body acclimated (don't remember how long but maybe 3 months or so). I would jump if the phone rang! Just remember that your Mom needs to be checked regularly for visual, hearing side effects. Not a bad idea to make sure that her thyroid is not out of whack and causing some of the nervousness. Also, not a bad idea to see a therapist so that your Mom would be able to confront and change some of the unreasonable beliefs that she has about this condition. She is indeed fortunate to have such a caring daughter-in-law. Wishing her the best.

@stsagris, Oh that poor woman!
Have you asked her dr about putting her on a mild sedative or anti- anxiety med? At least long enough to retrain her brain not to freak out or until she acclimates to the meds.

@stsagris Sorry to hear about your step-mother's anxiety -- but we sympathise and understand. I agree with others about the psychological side effects of the Big 3. But please also note that getting this diagnosis, and finding out about the risks and how weak your immune system is now, often causes a great deal of anxiety and emotional distress too -- at least for several months. This can take time to adjust to, but the person with the illness will slowly begin to adjust over time. Best of luck to you and your step-mother