Concern over flora after juice fast before pulling 2 teeth

I need to add back intestinal flora ASAP.

I am breaking a 14 day veggie juice fast so I can take Antibiotics to have two teeth pulled that have root canals. One is failing and abscessed # 2. Although that tooth is not at all painful or swollen or red - it has a black spot on the inside gum line. The other one is a cracked crown on # 15 that tooth was also crowned after a root canal. It is a tough decision to make to pull these teeth - But lack of money and health concerns are pushing me that way.

Anyway I have been slow to get on Antibiotics since I and concerned about the flora in my gut due to the juice fasting. I had not been taking probiotics or many supplements during the fast.

I have been taking natural Antibiotics Garlic, Lavender, Echinacea .....ETC. And the black spot has receded some in size and darkness.

I think the black spot surfaced after my # 15 tooth crown cracked. I just happened to also be taking Flora Essence 'EISSAC' herbal tea at that same time and did wonder if the Flora Essence was pulling out the toxins from under that # 2 tooth.

I do not have my wisdom teeth or Tooth # 3, so these are my very back top teeth I am considering pulling and while I hate to lose all that chewing surface I am still trying to work up my courage to have them pulled.

Back to my main concern right now- what to eat breaking this juice fast (I know to do this slowing but am unexperienced with this as this was my very first total juice fast.)and how to make sure my good flora are intact if I decide to use Amoxicillin before dentist pulling or dental surgeon taking these teeth out.

Is Kombucha good? Is it high in natural sugars? I want to avoid anything that feeds bacteria.