Does Doxycycline Help In Treating Pneumonia?

I ve been coughing only when I awake, nasty sticky thick sputum that is hard to clear but then fine the rest of the day. Then a few days ago it felt like my lungs had turned to concrete, I could barely breathe tho by evenings it was a little better. Then I d awake @ 2 a.m, unable to breathe. My chest was crackly, popping, wheezing, very noisy. I ve bad a headache and muscle pain, wandering earache, neck pain etc. my g.p. has diagnosed a chest infection and prescribed Doxycycline. Reading this health site it sounds like I have pneumonia,will Doxycline clear it?