If all the tests are negative for any infection or any specific disease,then nothing to worry. These things can happen due to altered physiology due to life style. Take good amount of drinking plain water( 5--6 litres/day). Have good sleep at night( >8 hours). Do some exercise like morning walk or skipping or go to GIM. Take multivitamine-multimineral tablet( like A TO Z tablet + vitamine E ( EVION
) for 1 month. You will be fine hopefully. You told all the tests are negative,but did not tell what was all those specifically. It will be better if Know those specifically. You may mail me at -email@example.com.