Let me address your concern one by one.
1. I hope you have completed the course of second antibiotic, which you are not allergic to.
2. If you have completed the course, then make sure that you are not taking any other medications. Since, medications usually cause heavy breathing, shortness of breath
, it is better to avoid any medicines as such unless they are required.
3. I do not know your age, I am sorry. However, it is advisable to get an EKG done to look for the cardiac status.
4. Repeat a chest X-ray now and look for signs of residual congestion on the lung fields.
5. It is better to consult a pulmonologist
and get bronchodilators prescribed (IF required only).
Hope this helps.
Get well soon.