Why does my blood sugar feel low? ?

i am hypoglycemic. my blood sugar normally averages around 80 and i feel fine until it starts to drop. My Dr said i need to keep it about 100. I just got through eating an 8 piece chicken nuggets. I feel like i am going to pass out my head hurts my heartbeat gets really fast just from walking up stairs and i start seeing bright lights. My blood sugar right now is 166. Are those symptoms bad?