What's wrong with me?

I had my first symptom 3 years ago. Every year, anywhere from August to December, I get sick. I get a very itchy rash covering just my face. It's red, bumpy, itchy, and swollen. This usually goes away in about a week. That's not all though. I also get a cough that stays with me from August to December. The only thing that stops the cough is Prednisone (an oral steroid). I've been to many doctors many times. I have been treated for bronchitis, asthma, allergies, and influenza. I had an allergy test and I am allergic to ragweed, but no allergy medicine works. I am an otherwise healthy 19 year old female. Please help me...I need a break from coughing!