Do I have depression? Which doctor to look for?

Hi doctor! In fact I would like to know what I truly have. Every day mostly in the morning I have a strange sensation, I feel the heart beat very strong, very trembling in the body and the desire to lie down without talking to anyone and crying for nothing, I feel fatigued to see people going to work or doing some work . It seems that the one who gets tired is me, after the symptoms pass I feel very sleepy, I already had heart examination did not give anything I am very afraid of losing my work, I already imagine when I go to work "Is it that I am with beginning of depression? I should be looking for a doctor?