I have to second what Montesquieu is saying. Always rule out the stuff that can kill you first. See your doctor - let them figure out if something is really wrong.
As for VCD - unfortunately, this has become a wastebasket diagnosis. True paradoxical vocal cord dysfunction (PVCD)results in stridor and cessation of activity. I have no doubt that there are hundreds of athletes that have been diagnosed with VCD because their "throat feels tight" when they exercise. They probably even may have been diagnosed by an excellent ENT or voice pathologist. However, IMHO, anyone that is running and can keep on running is not having a vocal cord problem. Your larynx regulates the intake of air into your lungs. If your vocal cords are adducting to any degree and limiting the flow of air (remember the relationship of the diameter of a pipe to flow is to Flow= diameter to the 4th power (OK not exactly in this case -turbulence, short pipe, pressure change, etc - but you get the point)you are not getting nearly enough O2 to keep on running. Keep in mind that there a lot of other muscles in your throat/ esophagus that can "tighten up" and they will have very little effect on your running.
Obviously, we've hit on a point that bothers me because I've seen a lot of people diagnosed with VCD who, I believe, do not have a vocal cord problem. They do, however, tend to respond the "VCD" treatment which basically entails relaxation techniques.