Hello Narasingha,
The causes for the symptoms as mentioned in your post can be:
1. Dietary deficiencies of certain nutrients like Iron, Vitamin B 12,
Folic acid, etc. which interferes with blood formation.
2. Inadequate hydration status & electrolyte balance of the body.
3. Any fluctuation in the blood pressure & blood sugar levels.
4. Hormonal & metabolic causes.
5. Stress, inadequate sleep, etc.
The reasons for difficulty in maintaining erection can be many such as
Hypertension,
Diabetes mellitus,
Atherosclerosis of the arteries, Neurological problems, Chronic illness, Prolonged intake of drugs, Stress, Smoking, Alcohol, etc.
So, investigations like
complete blood count, estimation of blood pressure & blood sugar levels will be helpful to rule out any pathological cause for the symptoms.
And it is also needed that you take certain precautions regarding your diet & lifestyle, such as:
1. Take a healthy diet with lots of fruits & vegetables.
2. Drink lots of water to maintain adequate hydration.
3. Avoid fast foods.
4. Avoid smoking & alcohol.
5. Keep away stress..think positive.
6. Exercise regularly & practice meditation.
Wishing you a Good Health.
Thanks & take care.