With PeptoBismol, you can take an acid blocker like Prilosec and Dramamine (for vomiting). Both are over the counter. Keep taking plenty of fluids. The cramping and nausea denote persistent mild grade intestine infection; so if these symptoms do not subside in a day or two; you would need to get a prescription of antibiotics from your primary care physician.
Please feel free for your follow up questions.
Infection may not be worsening, but it may be persistent and is not eradicating. There are not many home measures which are effective when there is a chronic infection, except keeping yourself properly hydrated, eating boiled vegetables and well cooked meals and fresh prepared soups. This may cleanse the intestines in a couple of day. But there are stubborn infection, which do not go away and may need some sort of anti-bacterial.
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