Why do i have "waves" of depression for like 3 days, then i feel kind of normal again for a few days, then really depressed again for a couple of day?

Depression: To answer this question, you really need a thorough evaluation with your doctor. You've listed a couple of problem areas, but haven't shared any medications you might be taking. Consultation with a psychiatrist would be of use also. Some mood disorders can present this way, but also environmental stimuli like work or relationship situations can affect your mood also.