Not sure what is happening.

For the past few nights I’ll be asleep and dreaming. In the dream, I’ll be taking or doing something that dosent involve any cardio or working out and I’ll start to struggle to breathe, I’ll be trying to breath in the dream and in real life and I won’t be able to. I’ll eventually catch my breath and start breathing again, but my heart starts beating harder and heavy than ever and I’m not sure what is happening