hi there, do not have such a low opinion about yourself and get out of this depressive mood. As your doctor rightly said the fever
could be caused by uti and continue the antibiotic for the prescribed number of days. You also may be anemic and so need to take iron supplements
or food rich in iron. The lethargy
can be attributed to the fever. Drink plenty of fluids and take rest for some days . when the fever subsides you will start feeling much better. Take care.