Hi welcome to Health care magic forum.
Thanks for calling H.C.M.
Most probably your problem appears to be anaemia
. I advise you to consult a physician for diagnosis and treatment.
Other causes may be gasric hyper acidity, diabetis, etc.
I advise you some diet recommendations as take more of green leafy vegetables, pulses, sprouts and protein containing foods to have iron and proteins
in the diet to build up blood and general health.