Brief Answer:
more tests needed
Detailed Answer:
Hi, i am a gastroenterologist.
Nausea for a month is quite a long time. There are multiple causes of nausea.
Most commonly it is a medication side effect, so if there is any new medication that you started taking, even if over the counter it could be the cause of your symptoms.
Hormonal changes can cause it, in your case as a male, thyroid hormone changes.
viral illnesses, or other illness from anywhere else in the body can cause it as well.
An ulcer in the stomach or
duodenum can cause intermittent blockage of the emptying of the somtach, causing nausea, but usually also
vomiting.
An entity called
gastroparesis (delayed gastric emptying) is also in consideration, usually seen in diabetics, but also in non-diabetics.
In conclusion, you need further evaluation and testing, preferrably by a gastroenterologist.
I can't suggest any other meds for you to take, as zofran is quite potent (usually given for patients receiving
chemotherapy).
hope that helped.