why would doctors not prescribe antibotics for an ulcer?

OK, let me rephrase it.

Not all stomach pain is an ulcer. Some stomach pain may be gastric reflux, which is NOT an ulcer, nor will not cause an ulcer in the stomach. Reflux may cause esophageal erosion, which may lead to a hole being burned in the tissues which is not the same thing as an ulcer caused by a virus.

If the pain in your stomach is caused by acid reflux tweaking the nerves in the base of the esophagus just above the valve at the base of the esophagus that keeps the stomach contents in your stomach when you hang upside down on a trapeze, then it would not be appropriate to give you an antibiotic, because that pain is not caused by any sort of microbial infestation digging in for the winter. If that pain is caused by acid reflux, then you need to take a proton pump inhibitor to reduce the amount of acid produced in your stomach at inapproprate times.

So to wrap it up. An ulcer is any hole in a tissue. It can be caused by either microbial action, or by acid erosion.

I take omeprazole to protect me from having my esophagus eroded to create an ulcer that is not microbially produced.

My statement that I take omeprazone is perfectly true when I say that it is to protect me from an ulcer, and not all ulcers are caused by microbes so an antibiotic is really not desirable nor would it protect me from getting an ulcer. You are not considering that there are other locations and causes of digestive system ulcers.

[and you can get an ulcer formed by erosion in the intestines if certain medications get through the stomach too fast and dissolve while being held in the tissues of the upper intestine which is not buffered against acid by a coating like the stomach is.]

Is that Omeprazole (Prilosec) dose correct? The only dosages it come in the U.S is 10mg, 20mg, 40mg (the 20mg is the OTC one). I’ve never seen someone given 500mg.

I found:

Maybe that is where the 500 mg came from?

Other than that, not a clue.