Why am i always sick?

it started about the time the swine flu was going around fall 2009. I was sick for 5 months, fevering, cold chills and wead with the feeling that someone punched me in the stomach along with a cough and sore throat. I finally kicked it and its back again starting the end of march. I am so depressed, i lost my job, all the doctors say theres nothing wrong with me but i feel like im dying. i have a little boy and its so hard to do all the things it takes to be a good mom with this constant illness. does anyone have a similar story?