I feel quite low all the day...my blood level is normal..what can be that?

Feeling low: Not sure what you mean by blood level; do you mean you aren't anemic? Low energy levels can be caused by many other issues like underactive thyroid, diabetes, electrolyte imbalances., lack of sleep, sleep apnea, depression, improper diet, stress...The list is very long. You need to have more evaluation than you can get here in order to figure out what is going on.