What Causes Persistent Dry Cough?

Hi i am female 29 yrs old and have dry cough for almost a month now...i did my lung X-ray which is normal with some cough in it...I did my blood test which shows my ESR level 92% and haemoglobin is 11 with mild hypochromic red cell morphology...lymphocytes are 42%....i am worried if i have TB...kindly help..there is no history of TB in my family both father and mother...i am too worried..