Why have i been sick this long?

it started a little over a month ago with just sneezing and a slight runny.. then to runny nose and coughing and now im coughing up very nasty phlegm a stuffy nose and sore throat. last night i had gotten a fever and it went away but now i feel like its coming back again. in the past month tho i moved from wisconsin to california and its been well over the 100s the past few days. but it doesnt explain why ive been sick this long. anyone have any idea why im this sick?