Depression during pregnancy

this is my 3rd pregancy I have a 3 year old and a 7 month old and I'm currently 9 weeks pregnant. Theres nothing to be sad or depressed about in my life I have a great husband and supportive family I just feel sad angry and depressed for no reason at all. Idk if it has to do with being tired and sick all the time. Anyone else have this happen. How did you cope.