No, lactobacillus is not the same thing as lactose. Not even remotely similar. Lactobacillus is a strain of bacteria that occurs naturally in our digestive tract. Lactose is a form of sugar that occurs naturally in cows milk. The body requires an enzyme called lactase in order to digest the milk sugar(lactose). When the body doesn't produce the lactase enzyme, or doesn't produce enough of it for the amount of lactose you ingest, the lactose doesn't get digested properly.
When sugars don't digest fully, they begin to ferment in the intestines. One of the byproducts of the fermentation is gas. This causes the flatulence that we experience, and also accounts for much of the stomach pain as well.
The fermentation itself occurs when the bacteria in the gut start to metabolize the lactose(sugar). This is similar to the process that occurs when beer is brewed. The lactose allows the bacteria in the gut to feed and multiply very quickly, which contributes to an imbalance of good to bad bacteria in the intestines.
Also, simple carbs like bread, pasta, wheat, rice, sugar, and potatoes can contribute to bacterial overgrowth, as well as possible yeast overgrowth in the body.