Running since 2001, why having problems breathing deep now?

Patient: I have some breathlessness and problems breathing deep when running. I’d say this has been going on for at least 4-5 months now and it means I’ve had to scale back my runs, which are no longer fun because of it (I have loved running for years, so this is depressing). Basically, it feels like I can’t quite inhale deep enough, like the diaphragm won’t let me? I run regularly and have since 2001, although I am no longer a long distance runner like I used to be. Since about 2009 I’ve had an inhaler, which I only very sporadically use. I found I usually only needed it after running very hard (like sprints), particularly in cold weather… but recently I had to use it twice to help with this breathing issue. I should add that last spring I also went to the ENT several times for sinus issues, which turned out to just be really bad postnasal drip from what he thought were structural issues (deviated septum and narrow airways, measured at only 400 milligrams on some breathing machine test, if that makes sense?) Anyways, since then the running-breathing issues have become worse. I’m finding this very frustrating as I’d like to increase my run mileage again, but even the half hour I do 4-5 times / week right now is difficult. What tests should I have done or ask for at my GP? Are there any I can do at home to test my lung function? One website suggested using a peak flow meter, but I have never used one and don’t know how to read it or what it could even tell me.Also, is there any possibility that this could be related to a larger problem with my lungs? I ask because I lived in Beijing for a year about 4-5 years ago and ran when I was there… I already had the inhaler when there but I hardly ever used it. I am honestly not sure how much air pollution could have damaged my lungs.Finally, I don’t know if it’s related, but I had a baby in March 2014, but I was able to get back to jogging/shuffling a month after she was born, and I did a 10K when she was about 10 weeks old. I felt fine through all that, and through the subsequent winter. However, last spring, along with the issues that sent me to the ENT, I was also having migraine problems. They did loads of tests (including MRI and CT of my nasal cavity) and found nothing. At one point, when I complained about digestion issues I was having (changes in bowel movements) and mentioned family history of colon cancer, I even got a colonoscopy — also showed nothing…. My blood work only indicated a low vitamin D and semi-low iron, so I now take a high dose of vitamin D each day prescribed by the doctor. This has helped significantly with the headaches. I do think some of this is related to my crazy hormonal fluctuations (I’m 35 and have issues around ovulation and just before my period that I never had before), but I don’t know if it’s related to the breathing issue? I’m just frustrated because running is my outlet for stress and anxiety, and it has generally kept me healthy and happy, and I like it more than the restorative yoga I do.

Symptoms: Breathlessness and deep breathing problems with running