It sounds like your on the right track by trying to reintroducing good bacteria into your body and taking olive leaf. I think the diarrehea can be from a number of bacterial or viral infections. Have you considered the possibility of food poisoning? Also do you know how pure the olive leaf extract is? Does it contain oleuropein or elenolic acid? Both are active agents, depending on how much the extract contains could determine how effective it will be. Elenolic agent specifically targets bad bacteria.
If you are willing to purchase products, I can recommend a small cocktail that should have great results with viral/bacterial infections and accompanying diarrehea.