You say you've had 2 x-rays that have been clear, is this since you started vaping? Is this cough the same cough that you had as a smoker that just didn't go away with your switch to vaping or is it different? Do you only cough when you vape? Have you had pulmonary function tests done? Have you recently been tried on antibiotics for bronchitis?
I actually am a doctor, but you have to keep in mind I'm not your doctor, or anyone else's on the forum. A few possibilities come to mind, but keep in mind that you need to see your own doctor for a diagnosis. I'm thinking maybe acute or chronic bronchitis, PG allergy, or most probably COPD. I'm sure you'd be advised to quit vaping and not to start smoking. I'd definitely agree with the not smoking, but as to quitting vaping, that's going to be up to you and your doctor. Quitting vaping is easier than quitting smoking. Just gradually lower your nicotine level until you reach 0mg, then see if you can quit. Some people do find it possible to lower the nicotine level, but can't get to 0mg. Nicotine replacement products or snus would help in that circumstance.
I actually am a doctor, but you have to keep in mind I'm not your doctor, or anyone else's on the forum. A few possibilities come to mind, but keep in mind that you need to see your own doctor for a diagnosis. I'm thinking maybe acute or chronic bronchitis, PG allergy, or most probably COPD. I'm sure you'd be advised to quit vaping and not to start smoking. I'd definitely agree with the not smoking, but as to quitting vaping, that's going to be up to you and your doctor. Quitting vaping is easier than quitting smoking. Just gradually lower your nicotine level until you reach 0mg, then see if you can quit. Some people do find it possible to lower the nicotine level, but can't get to 0mg. Nicotine replacement products or snus would help in that circumstance.