Sensation of not enough air

Greetings,
I am experincing a sensation like I am not getting enough oxygen even though I am breathing properly. I have been having this sensation on and off for about 3 months. I haven't had it for quite a while until today when after my excersise session of running and light weights which ended at about 1.30pm, I started feeling that way at 3pm it has now lasted about 2 hours. I also experince a dull ache on my lower left chest just below my left breast. Sometimes I get the same pains on the right side though rarely.It varies in frequency but comes and goes even when i am at rest. Its a dull ache. I am not feeling any tightness in the chest nor any shooting pain from my left arm.
I am a hypertension patient having been diagnosed with horse shoe kidneys at age 16. I am on a combination of Lopressor 100mg and Tritace 5mg daily. I have been very stable on these drugs and my last BP check was 130/80. I am 33 years old and weigh 118kgs I am 6 ft tall.
I have been excersing regularly as I want to bring my weight down. I excersie 3-4 times a week my excersie is mainly running on a treadmill for 30 minutes during which i run about 2.5 miles. I have just added light weights for abut 15 minutes. I have been to my doctor a couple of times and he tells me everthing seems okay. About 2 years ago I had a full caridac examination which included a stress test, ultra sound and an ECG all of which were normal. I am on a diet of mainly fruit and light meals. I do not drink any alcohol or smoke neither have I ever engaged in the practice.
Should I be concerned?

[Cleveland Clinic]

runnsalot,

Good job undertaking this great lifestyle modification. It will have a huge impact in the long run.

If you are continuing to have a persistent chest pain or shortness of breath you should be evaluated by your physician. There are alot of causes, even noncardiac ones such as musculoskeletal pain and exercise induced asthma that could be causing your symptoms. However, if you are actively having shortness of breath well after exercising, you should be evaluated.

good luck