Mental health

I have been really really down lately. I don't know how to explain it. The stress of my job as a Hospice CNA, student full time, a Maid of Honor for my twin sisters wedding, long distance relationship...I have a lot of shit in my plate. I feel like I'm going crazy, and I have zero confidence or energy to pick myself up anymore. I even called in sick to work this morning because I physically cannot motivate myself to get out of bed. I feel like a horrible person because I have a job that I need to take care of others, and I can't even take care of myself. I am really thinking about getting back on depression meds. I also think my biggest stressor is work. I have witnessed more than 50 deaths in the last two months. Is this post traumatic stress? Am I just crazy? I don't wanna let my work down, but I don't know what else to do. How can I make them understand what I am going through, without firing me? I really really need some advice and words of encouragement to get me through the rest of this semester.