May be depression. What is all this.

Hi, My hubby went thru a train accident during which i handled everything well as per others. But now i just dont feel anything. Rather i vl become very sensitive or else just blank.I laugh at jokes but suddenly again in a sec, i just go emotionless or blank. I dont know wat is wrong with me but i just dont feel ok. May be it is the impact of wat happend. or may be i just dont get it. I m unable to concentrate properly otherwise i just loved to be number 1 in my work. its a feeling like u know where u r most of the time sad about something or else u just feel nothing. i pretend to be happy sometimes or m actually happy, its just confusing. m becoming short tempered as well. Please help. what is all this.?