Hi Jake----
You can buy probiotics at any reputable health food store. You can start with FOS (fructoogliosaccharides), and the brand I buy is NOW. Another one is Primal Defense HSO Probiotic Formula, made by Garden of Life. You won't need to worry about "ingredients" with either of those. After 3-4 weeks, you can begin a multi-strain, live-culture acidophilus. The first two will make the environment better for the acidophilus once you start it, and it will flourish readily. The acidophilus I take is at least six strains, and I get the eight strain when I can. The important thing is that it's live-culture.
Best wishes for renewed good health.