I cant go 2 minutes without coughing? advice please?

Ive had what i think is the flu for 2 weeks, and it keeps getting worse then slightly looking up again, and then bak down to the bottom again..symptoms include/included headache chills fever muscle aches and pains ***** move out of bed. Nausea loss of appetite etc..so many things..and now i have this really awful cough and i just cant stop..nothing will help it, ive tried loads of different cough medicine..its really chesty and deep, i dont really know how to explain it..lik deeper than a "smokers cough" ive been coughing so much now that its starting to hurt right through to my back and its given me a sore head now. =[ Its driving me mental..i think im getting better and then wham everythings up the left again.