J.B.
Did they test you for H. pylori? That's the most common cause of ulcers, followed by taking NSAID pain relievers (aspirin, naproxen, ibuprofen, etc.). Presumably the blood work that came back normal looked for that, but make sure they did test for it. If you have it, you need an antibiotic.
Are you taking a probiotic? A probiotic can help strengthen and heal the lining of your stomach and the right one can actually fight the bacteria that causes ulcers and makes symptoms flare up. Probiotics are a wonderful addition to anyone's health regimen and really help with keeping your digestive tract running optimally.
The foods and beverages that you've listed don't cause ulcers, they just make them flare up. So once your ulcers are healed and you address whatever caused them, you should be able to eat normally. Technically, Prilosec isn't antacid, it's a PPI, which is a class of drug that reduces the amount of acid you produce. True antacids (Maalox, Tums) don't do anything to treat ulcers. So to answer your final question...ulcer sufferers shouldn't take antacids anyway because they don't help, and once your stomach heals, you shouldn't need to continue with the PPI. Prilosec has a lot of side effects when used long term, so it's best to get your gut healthy instead of relying on these. Our gut has more neurotransmitters than our brains and is the center of our immune system, so taking medication for a long time that affects this system messes with nutrient absorbtion and other key functions of the GI system.
I hope that you get to the root cause of your ulcers (if that's what they are), solve that problem, heal and enjoy a normal, healthy tummy again soon.