Hi. Thank you for the query. As I went through the details provided there is more than single differential is likely. So he needs a few evaluations for further start of definitive treatment. 1. He has to do an ECG and Blood sugar test ( FBS & PPBS) with serum electrolytes , serum creatinine and blood urea. 2. His BP is quite high . He needs to control his Blood pressure . He is known hypertensive .So do visit his consulting doctor for the change of antihypertensive. 3. You have mentioned that no chest pain . But in elderly cardiac issues do not present typically as chest pain. So Take him to nearby clinic or hospital and try to get the above evaluation and investigation done. There is likely that all result may come within normal range and diagnosed as acute gastroenteritis . But you should not neglect the issue when he is elderly with h/o hypertension.To rule out other possible causes you need immediate evaluation in a hospital with BP control and start of any antibiotic if required with supportive. I hope that this will help you and well soon to your husband. Thank you.