Itchy heart

Patient: Itchy heart? so iam getting in to shape and have lost 45 lbs in the last 4 months. ive been lifting and doing carido elliptical at first but iam moving on to running and been doing so for over a week. ive been doing 30min at 5.0-5.5 mph and bumped it up to 6.0 mph for 30 min just a guess i believe my heart rate is probably at 184 for 30 min. ive had a itchy feeling in my heart from the new harder routine iv felt this once before and it goes away after a day or 2 of rest. i am 28 yr 5,7 165lbs. what is the cause of the itchy heart feeling am i pushing to hard mabey my blood vessels are expanding is 184 for 30min too much physical i can do this speed with a little pushing. what should i keep my heart rate at to run 30 min? thank you

Symptoms: itchy heart