Is there any loss of blood in stool..Check your hemoglobin level , vit D3, vit
B12 ,serum
calcium level and
thyroid profile..
Take adequate water , juice, ors to avoid dehydration which may be a possible cause
Check your bp, if it's low, or postural hypotension can also be the reason
Improve your diet, avoid constipation by including adequate fibre in diet
For further discussion u can connect