Asthma

If you suffer asthma then the dream will probably be illustrating something about the physical or psychological cause of your condition. See: Air

Otherwise it probably depicts feelings to do with struggling to survive, or being smothered in a relationship or situation, or maybe some form of anxiety. This dream experience can arise from powerful fear or anxiety and not due to any physical problems. A response to anxiety is sometimes that of holding the breath, but it can also cause difficulty in breathing. See the dream work under nightmares.

Useful questions are:

Am I experiencing heightened stress or fear about something?

Am I meeting a fear of death or illness that I am not really allowing to be felt or expressed?

If I imagine myself struggling for breath what emerges; what am I seeking or facing?