I’d say the first step is recognizing the need for help.
One that doesnt involve a lot of sugar because it would keep her heart from acting up and giving her a heart attack
Yogurt
yogurt contains mostly carbs.
You could try to put cold ice over it to calm down the bruising and then use a cloth and damp it in hot water(warm water) and wipe the bruise properly so that the blood can circulate properly. If you are having troubles breathing then why to relax your muscle, because if you are tense right now it will only make things worse.
And if it really hurt go to the hospital, dont take any risks.