Constant Coughing!!??

Poor Liam has been coughing consistently for the past almost 5 months now! At first when the cough started we were told it was bronchitis! They gave us some medicine and when we went back for his check up they said the bronchitis was cleared up and his coughing should subside soon. When it didn't, I called the dr and the nurse told me it was that time of the year and it was normal for them to cough a little. I explained that it wasn't a little...it was pretty consistent and a very wet cough at that. We'd gone back in a couple of times to just get his lungs checked and every time they said they sounded clear and to just try natural remedies the nasal aspirator to get out any mucus in his nose and throat, try using a cool mist humidifier, prop up his crib mattress, etc.....but nothing EVER worked!!?? So...I called my friend Val. Being a pediatrician herself, she's really my lifesaver SOO many times!!! Anyways, she told me to try either claratin or zyrtec for children. So we did that....we started Liam on zyrtec. We did that for about three weeks! We didn't really notice a change in that....so she told me to try claritin, like many people some medicines don't work as well as others. So Liam's been taking Claritin now a week this past Thursday and still coughing!! Kristin let me borrow her nebulizer (she had from when Nathan had asthma bad) and some albuterol...and I gave Liam two breathing treatments...one Wednesday night and one Thursday night. HOWEVER, the unfortunate problem with albuterol is that it speeds up their heart rate...SO, Liam would wake up in the middle of the night WIDE AWAKE!?!? So, FINALLY I went in to the doctor Friday and demanding SOMETHING be done!!! I couldn't take it anymore....this poor child's been coughing sooo much and it just CAN'T be normal!! We KNOW he's allergic to fresh cut grass for sure! I picked him up from the babysitter one day, they had mowed the lawn that day and his face was swollen, his eyes were all red and tearing! So I told the dr that I felt he definitely had allergies...maybe that was the problem!? Our dr ordered a chest xray to be done right away to check for any other issues we may not be able to tell about and then he said after seeing that he might try and prescribe him singulair...which he says will help if the issue is an asthma/allergies problem. So HOPEFULLY something will help soon!! In the mean time the dr prescribed more albuterol and suggested maybe we try doing the breathing treatment during the day and see if continuing that helps anything?? I guess time will tell but GEEZ...I really hope something helps soon! My poor boy.....