Is there anything i can take to prevent yeast infections? i am going to be on strong antibiotics for lyme & 2 co-einfections for a long time.

Get a 2nd opinion: The best way to prevent yeast infection is to avoid unnecessary antibiotics. Proper treatment of lyme disease & other tick borne infections can usually be achieved in about 2-3 weeks - if treatment is prescribed >4 weeks consider a 2nd opinion with another expert (it never hurts to ask). Alert your doctor of any new symptoms of yeast asap rather than take a preventive antifungal for yeast.