I'm not a medical doctor, and can only tell you what my son's doctor prescribed for him. He only prescribed the neomycin for 7 days, and the lactulose for 1 dose which produced diarrhea and thoroughly cleaned out his intestine. This was the goal. However, if you see that the lactulose doesn't give you the diarrhea to clean out your intestine, then you should take it until you get that desired effect. Be careful because usually the diarrhea is uncontrollable and kicks in the following day. Try to do it on your day off where you can be at home near the bathroom. My son did repeat the lactulose the following week and then every 2 weeks, and finally once a month, until his odor went away. I guess it wouldn't have hurt him to have extended the neomycin a little longer, as the odor took a couple of months to go away. Perhaps with a longer treatment of neomycin, he would have had faster results. I don't really know. Nonetheless, we know that there is a window of 7 to 30 days for this med. This neomycin treatment is a one-time deal only, so you shouldn't be repeating it.
About the probiotics, you definitely should begin taking it after your 1st gut cleansing with lactulose. The brand name he uses id Jarrow Formulas, Enhanced Probiotic System (EPS), Jarro-Dophilus. They are enteric coated vegetarian Capsules that contain 8 species, including Bifidobacteria longum BB536. Even though it claims to be Room Temperature Stable and no refrigeration required, I make sure that my Health Food Store has kept it in their refrigerator, and I keep it in my refrigerator.
The article ends with a final note: "...there is a chance that you will precipitate a die-off of bad bacteria in your intestinal tract. This can lead to gas, stomach rumblings and cramping for up to three weeks." So if you feel any of these symptoms originally, keep taking them until the die off process ends (not more than 3 weeks). Just keep in mind that it is the healing process. Then it should all go to a healthier state. My son was finally able to wear a belt afterwards when he had not been able to do that as far back as he could remember because his lower abdomen was always so bloated and painful. He takes one or two pills of probiotics daily and plans to keep taking them as long as possible, preferrably forever.