Hello Rum***** thanks for your question your husband is experiencing high grade fever, restlessness, severe diarrhea and vomiting. most likely these symptoms are due to Food Poisoning or Gastroenteritis, which is a infection in intestinal tract. It also depends upon food which was taken before first episode, as in most of cases 6-24 hours are needed by infectious agent to manifest its symptoms. The weakness he is experiencing is only due to ELECTROLYTE imbalance due to severe diarrhea and energy deficit. Decreased potassium, sodium are main body ions which are responsible. To correct this ask him to take plenty of Oral Rehydration Solution (ORS) or Electoral Powder, which not only improve electrolytes but also improve glucose. Second to treat cause you have to start with good antibiotic which covers all major enteric pathogens, as per my opinion combination of Ofloxacin and Ornidazole will be more than sufficient. Also for vomiting if he is able to tolerate oral drug then give him Pantoprazole and Domperidone combination, but if not able to tolerate due to vomiting, all drugs have to be given in injectable formulations. Usually in a number of cases body counteract to correct gastroenteritis itself, so you need not to worry, just maintain good fluid intake, don t give plain water as it will worsen imbalance. Banana, warm water will also provide symptomatic relief. thanks hope I solved your question kindly rate.