In recent weeks i've been coughing a lot. i don't have fever, my lung x-rays is ok and basic blood test is ok (w/signs for inflammation). what is it?

Cough: There's a good chance your cough is trailing from an upper respiratory infection you may have had (runny nose, sore throat, fever, etc.). That type of cough is known to linger and will eventually go away even without treatment. Allergies is another chance especially with symptoms of runny nose, red, itchy eyes, etc. Sometimes lung xray is negative but the problem requires more in depth studies-ct.