It may not be because of e-cig.
Stop e-cigs for a week or two.
Try the patch or gum, just for a couple of weeks.
You might be having an Anaphylaxis Allergic Reaction to the Propylene Glycol in the juice.
Anxiousness, the feeling of weight of your chest, breathlessness, palpitations are not little problems. You need to figure out what is going on.
If you have existing medical conditions, talk to your doctor about vaping.
If you have new symptoms when vaping, talk to your doctor about vaping.
Looks like we got plenty of response: go to the doctor.
Oh and don't vape yourself into a coma

while waiting for an appointment,
or is that only a U.S. thing?
Rocket