I'm very sorry about your pain,
It might be due to some muscle injury
which has led to spasm of the injured muscle to prevent further injury.
Since the same muscles are essential for inspiration it's causing pain whenever you try to breath.
Give rest to the muscle.
Pain killers and muscle relaxants orally will help.
Local irritants will also give symptomatic relief.
Kindly get them prescribed from your doctor.
If the pain worsens or still persists kindly visit your doctor and get medical help