Can bacterial food poisoning cause a red blotchy rash that doesnt clear up, even with benadryl (diphenhydramine). what is the rash...what do i do?

Yes. From toxin: Bacterial stomach and intestinal infections often cause rashes. The rash is a result of toxin production from the bacteria. Some staphylococcal infections release a serious toxin that can cause shock. Salmonella also can release a serious toxin. Viral infections also cause blotchy rashes. Make sure you do not get dehydrated. Keep fluid intake high. Take benadryl (diphenhydramine) every 4 hours. Apply cool towels

Other considerations: I agree that this could be related to an infection. If the rash is associated with any respiratory or swallowing difficulty this may be a severe allergic reaction. Your physician should be notified if this does not improve or is associated with other symptoms. Food poisoning tends to improve rapidly but may cause dehydration. Allergic reactions may last days or longer.