thank you for your query
your symptoms seem to point out towards anemia
it means that your blood hemoglobin
levels might be low.
this leads to a decrease in body's cells capacity to carry oxygen
hence the feeling of being tired in the day.
for combating this you need to eat lots of green leafy vegetables and iron containing foods
and stomach problems could also be because of your diet.
try to include fresh fruits and fiber-containing vegetables.
i would advise you to get a Complete Blood Picture done a and a general health check up done to know the levels of your Hb.
wishing you good health