1. Because you saw it on TV. 2. Because your Doctor was tired of hearing you whine. 3. Because you have a microbial infection.
Why do you want me to tell you why you were prescribed a pill that inhibits gastric acid secretion (proton pump inhibiter)? You should tell me what your symptoms are first as well as any tests that were performed and the results. Surely you can see that it is a silly to say I am taking such and such drug tell me why since the same drugs are used for multiple indications.
I don't remember it except that it vaguely had something to do with numbness in your extremities and a pain in your back and wound up being a sinus infection that had somehow worked it's way into becoming intracranial. Peptic ulcers in combo with antibiotics and Reflux with just the gastric acid inhibiter are common reasons for gastric acid inhibiters.