The breathing part sounds like you could have sleep apnea. In sleep apnea, your breathing stops, or becomes very weak, while you are sleeping until your brain wakes you up and you take a breath. This kind of sounds like what is happening in the dreams. I think you should definitely have this checked out. The first dream, about being in a medical place, also seems to be a message that there is something medically wrong. Death in a dream can also represent change, so the dream about being afraid your breath slipping away could have to do with a fear of change - the rollercoaster could have to do with taking risks. But I think you should definitely have yourself checked for sleep apnea first.
None of that is true lol nevermind i thought this was a dream interpretation place. Not medical advice. Sleep apnea? No lol
Dream interpretation means trying to figure out what your dreams mean. One of the things that your dreams do is make you aware of problems in your life, including things that might be physically wrong with you. In his work on the interpretation of dreams, Freud wrote of going to bed thirsty and dreaming that he was drinking lots of water. I suggested that you might be suffering from sleep apnea, because the experiences in your dream are very similar to what happens during sleep apnea. Since sleep apnea can be life threatening, I thought it was important to check it out before looking at any other interpretation. Have you been tested for sleep apnea? Has anyone ever told you that you snore loudly? Another thing to consider is that during REM sleep, everyone's breathing slows down and gets more shallow. This is normal, but sometimes part of your brain interprets this as their being something wrong with your breathing and you can dream about being choked or suffocated. During sleep paralysis, a state in which you are partly in REM sleep and you are breathing this way, it is common to hallucinate that you are being choked or suffocated or someone is crushing your chest. As I said earlier, if you are looking for a non-physical explanation, your dream could have to do with a fear of change or taking risks, but I think it is important to check out any physical problems first.