>>19090250
If no one else has said it yet, antibiotics will fuck your shit up. Also beware coffee, alcohol, sugar, and processed junk. You want more "good" bacteria than "bad" bacteria in your gut. You need to encourage the "good" bacteria growth by eating foods that they thrive off of, and avoid foods that "bad" bacteria thrive off of. This will help to adjust your gut bacteria towards being "healthier". Fermented foods such as sauerkraut and kimchi can help, and probiotics like greek yogurt and kefir milk are also beneficial.
TL;DR Stop eating/drinking garbage. Eat more vegetables/fiber. Get a head start with probiotics.