I would certainly find a good pulmonologist. I tried for 11 years to determine why I became short of breath walking up stairs or when using certain cleaning products. I went through 3 doctors before I found one willing to do all of the different asthma test. He said I had adult onset asthma. I had gotten to where i couldn't push my kids in the stroller or push a shopping cart without becoming short of breath. I would ask about a methacoline challenge test. This is the test that eventually got my diagnosis.
There's "asthma" and there's "chronic asthma". Almost anyone can experience an asthmatic period under certain circumstances. You really need a work-up with a physician, but preferably a pulmonary evaluation at an asthma clinic. They will check your expiratory volume and see how it changes with medications. Anyone who has this problem should carry an emergency albuterol inhaler. It's impossible to say what is wrong with you. Needless to say, you require an in-person examination by an M.D. An x-ray will probably not show much. One test I recommend is to purchase an expectorant, such as Robitussin. If you cough up yellowish mucus, you have a lung infection that needs to be resolved.