Its been two months since i got these breathing difficulties,i ussually feel it at night time,when my body was relaxed and im going to sleep..i feel a sudden trouble breathing ang my hands and feet feels so cold and i shiver.i feel cramps in middle of my stomach..sometimes i feel dizzy..it feel like i would sleep al of a sudden..I have trouble sleeping because im afraid that i have might have a heart attack,the doctor advice me to have a urinalysis,FT4,CBC but its all have normal impression.i also have an ECG but its also normal..whatmight have be the problem?? Im 24 years old i quit smoking since I feel this trouble breathin and non alchoholic drinker..could this be an anxiety problem??My doctor advice me to take propranolol for a month 20mg twicea day and hydroxycine before bedtime for 3 days..but they cant diagnose my helth problem..please help