Feeling low

Today I have disciplinary at work for being off sick. I deal with alot of the public everyday (i work on the railway) and in the last 2 years I have had 2 people die, the 2nd person who died happened in march this year and just 10 days after that I had to deal with a drunk person and an ill person, I ended up having a panic attack about going to work....I couldn't breath, I just kept thinking what else could happen. My doctor upped my dosage of antidepressants and signed me off for 2 weeks. The company know I'm on antidepressants but I feel as though they think I'm faking it. I had a bad childhood and alot of my issues stem from that but the management at work make me feel as though I'm going crazy, that it's all in my head and nothing is wrong with me. I was diagnosed with depression anxiety at the age of 21 (I'm 31)