several hours ago I suddenly became very faint like I was going to pass out, my hearing began to fade in and out, and my sight would go and come and then go again, Its like I was going to pass out only I didnt, instead I stayed conscious but experienced the symptoms for nearly 15 minutes and everything felt as if it were moving very fast. My heart was also pounding and I had this funny metallic taste in my mouth and my breathing became slow and labored. I did not feel nauseous, but felt as though my body was about to just shut down. Should I be concerned?