Having Vomiting And Heart Problems. Feeling Weak And Dizzy. Reason?
Your concern about your grand father's health is well placed. That he is vomiting clear fluids indicates that all the food and bile have been expelled and only the gastric secretions remain, which are clear in appearance.
While vomiting may be due to a number of causes, the most likely cause is gastroenteritis, which is an infection of the stomach and bowels or else, there may be an obstruction of the bowels. Presence of diarrhea supports the previous cause and presence of constipation, the latter. In both cases, considering your grandfather's age and past medical history, he needs medical attention as this is indeed a cause for concern.
Your grandfather would have become quite dehydrated by now due to loss of fluids. Repeated vomiting also causes loss of electrolytes (sodium, potassium, chloride) from the body and also alters the acid-base balance of the body. This is causing the weakness and dizziness that you have mentioned. If this is not treated soon, further loss of electrolytes can impair the functioning of both brain and heart, leading to confusion, seizures, coma and even death.
In my opinion, your grandfather needs to see a doctor so that he can be assessed for all possible causes of vomiting. He will also need to get his blood tested for serum levels of electrolytes. He may need intravenous fluid replacement. Till he sees a doctor, please ensure that he takes adequate amounts or fluids, preferably oral rehydration solutions (ORS).
I hope this helps you. Best wishes. May your grandfather get well soon.