Asthma, allergies, gerd?? Need advice!!

Beginning in June when ever I walk outside I feel as if I'm having an allergic reaction. I'm on flonase and zyrtec which control all allergy symptoms except post nasal drip and feeling inflammed in my lungs and back. I'm on 180mg of pulmicort once a day. I thought it was helping but it was towards the end of July so may have just been low pollen days. As soon as ragweed started getting high my inflammation and shortness of breath have gotten much worse! I've been to the er three times and to my allergist at least once a week. I was first prescribed 20mg of prednisone and I felt the same throughout five day course. Didn't get worse but no improvement. I was off a week and then symptoms got a lot worse. Then went on 20mg for two days then upped to 40mg for two days. Didn't help and face turned bright red and my skin felt like it was on fire so I stopped taking it. Allergist and doctor feel that it's not asthma because oxygen intake has been at 99 to 100 every time i go in. This is after taking a breathing treatment before I go so not sure if they are factoring that in. I went to urgent care without taking albuterol and my oxygen was at 95. I have a peak flow meter which I have been at 400 all summer. A couple days ago I was breathing a 350. My doctor suggested maybe I am just having acid reflux?? Just wondering what other people that experience asthma or acid reflux think about this. Thanks
My symptoms
Post nasal drip
Occasional sneeze
Inflammed feeling in chest and back area
Tightness and occasional shortness of breath
When I lay down I feel pressure and tightness in my back
Symptoms usually worse at night
Wake up gasping for air.

Thank you! I Didn't know that about vitamin d defiency. I was taking a prenatal when they started but I've never been tested for a defiency so who knows if it was enough. I'll ask my doctor about it. I've been begging to be upped from my once daily 180mg pulmicort dose and they refuse to do it and told me they will no longer refill my prescription of it. At this point I feel like it's the only thing somewhat helping me!

Thanks for the response! I appreciate any advice that I can get. I have been feeling better for the last two weeks then Saturday was at a friends house who had opened windows and now I feel completely inflamed again. It's all in the middle of my back and through both shoulders. I have been getting short of breath as well. I'm calling the doctor tomorrow. How did you finally get the inflammation to go away. I've been taking pepcid once a day. If I take it twice my stomach cramps.