there are three parts of your query first you feel dizzy. your toes stuck and loss of balance. these need to be looked into by a neurophysician. you can proceed further for workup if he really finds anything on preliminary examination.
second is your nervous breakdown
for which you are trying to do something on your own. you may seek opinion of a clinical psychologist
for this and do as per their advise.
third is fear of heart attack
, what is your age? if you have any risk factors like diabetes
. blood pressure , smoking etc. can you walk jog, use stairs and run without any chest discomfort
or undue shortness of breath? if you can do so without problem and you dont have risk factors you probably need not to worry much. still you can discus more with details next time