My 4.5 yr daughter had a dry cough for 8wks after a cold. she was on antibiotics because the dr thought she had a sinus infection. her cough started two days before her antibiotics ended, so i thought it was a new illness. Gave it some time, no other symtoms, just the cough. I felt just like you do, because everytime I would bring her in, every 2-3 wks, the dr would say something different. At first it was, oh, she's just getting over a virus, next visit, her nasal cavity is a little red, lets try some allergy meds and when the allergy meds did nothing but make her a totally different child behavioral wise, I brought her in again and it was lets do another dose of antibiotics,maybe her sinus infection never fully cleared up and was just suppressed by first antibiotics. So gave it to her and a few days later, the coughing finally stopped. I guess I won't know for sure until next tree pollen season because the season ended around the same time she was on the 2nd dose of antibiotics but I was so relieved when the coughing stopped. It was almost as if no one believed me when I said she was coughing all of the time, even my husband started to say, well she's really not doing it all day. He's at work for 12 hrs so how would he know. Trust your gut, if you're not happy with the outcome thus far, either see someone else or ask more questions. Good luck. I hope the coughing stops for her and you as well soon.