Suggest Cure For Sickness In The Stomach

Hello my name is Katie Depew, and I am desperatly seeking answers to my fathers death. He died 10 years ago and his death was ruled unknown. Now that my siblings and I are adults we would like to get some answers. He first got sick in the summer of 1997 he would have “episodes” that would last about 3 days, the 1st day he would be feeling a little sick, the 2nd day he would be very sick and the 3rd he would be recovering and by the 4th all would be back to normal. His episodes consisted of High fever chills severe headache nausea and vomiting abdominal pain loss of appetite fatigue aches and pains restlessness dizzyness due to migrane cold/clammy dropped heart rate achy legs to the point he couldnt walk low blood pressure[ top number in the 60’s] These “episodes” started out only happening every few months, then got closer together and the last month he had one every week. Poisonong and rocky mountain spotted fever were ruled out. He also was hospitalized and sent to the mayo clinic in minnesota in july of 1999 for further evaluation and they to were unable to diagnose him with anything. Below is a copy of his medical examiner report. Thank you so much for your time and aadvise. Any information you can help me with would be greatly appreciated, ever little bit helps