Hello User.
It's happen due to psychological trauma that you had due to demise of your close one.
Acute stress reaction can happen due to major psychological trauma or any big indent that suddenly happen in anyone life ..
And, anxiety symptoms you are having in that breathless, haearbeat heard by your self all are part of it ..
Next Steps
medications if that interfere with personal or social life and counselling and detailed assessment
Health Tips
psychiatry consultation for further assessment and evaluation...