Heart rate slowed to low 50's. always 80's - 90's. on 2 occasions in the last month it was so slow i became dizzy. lasted +_ 3 min. exercise less now than before. worry or normal?

See a doctor: Looking at your history you probably have a heart condition and need to be worked up. If you are dizzy when your heart rate drops to 50 you need to call an ambulance next time.

Be seen: Would definitely recommend you be seen to rule out any major and possibly even life threatening cardiac arrhythmia. A holster moniter can sometimes be used to determine what is actually happening when you are experiencing those symptoms.