Is this low blood pressure or an infection loss of energy, fatigue, loss of appetite, nausea no history of high blood pressure or diabetes... male: 53 years old

The : The only way to know if you are dealing with low blood pressure and/or an infection is to a have complete medical evaluation by your doctor. Your symptoms are non specific which is i can't tell you either way. You may have other issues going on (i.e. Thyroid abnormality, anemia, etc.) if you have not had your yearly physical now would be a good time. If you have then schedule a routine office visit. Best of luck.

Fatigue, nausea: The combination of fatigue, nausea, and loss of appetite may be related to an infection in the stomach/intestinal tract or the gallbladder. There are several other reasons for these non-specific symptoms, so it's best to see your physician for further work-up. Low blood pressure usually causes lightheadedness, dizziness, fatigue.