Hope you are feeling better by now, but if not, get a chest x-ray. I had your symptoms (as well as cold/flu symptoms- chills, etc.) and my doctor tried the hit-or-miss method as yours did (antibiotics, etc.) however, they didn't help... it turned out that I had pneumonia but the antibiotics weren't at a high enough dose to do anything.
Hope you are feeling better by now, but if not, get a chest x-ray. I had your symptoms (as well as cold/flu symptoms- chills, etc.) and my doctor tried the hit-or-miss method as yours did (antibiotics, etc.) however, they didn't help... it turned out that I had pneumonia but the antibiotics weren't at a high enough dose to do anything.
Personally, if you feel your doctors aren't giving you the help you need then I would go see a respiratory specialist. About a month ago I started having shortness of breath. It worried me so I went to my doc and she said that it might be from stress/anxiety so she prescribed me Paxil. I took that and it didn't seem to help so I stopped taking the Paxil. 2 weeks after I went to the doctor I started feeling pressure on my chest and still had shortness of breath. I went to the emergency room and they said I had bronchitis so they prescribed Zithromax. It helped tremendously, but I still have shortness of breath. I had seen 2 doctors w/in 2 weeks and still had SOB, so that's when I took it amongst myself and made an appointment with a respiratory specialist. I went and they did and EKG, breathing test, and ling x-ray. All of which came back normal. They said that they did notice that I had a rapid heart beat 140 bpm and that it worried them. I figured that was b/c I was nervous because of being at the doctors office. They said even for a nervous person it was still high. The respiratory specialist said that since my lungs aren't the problem that I could have a form of heart disease so he recommended that I go to a cardiologist and have an echo done. I went yesterday for the echo, but won't know the results until I meet w/the respiratory specialist again. The respiratory specialist has been awesome. He has made all the necessary appointments for me, something the other doctors I went to wouldn't do. He told me that he wasn't going to stop until they got to the bottom of why I was having shortness of breath and until they could help me treat it. I know trachycardia is having a fast heart beat and it can cause you to have shortness of breath.
I would deffinatley recommend going to a respiratory specialist.
It's better to be safe than sorry!!
I think you may want to check out some information on pulmonary hypertension. There is a website called PHCentral.org that you should just try.