What Causes Headaches,dizziness And Palpitations With Chest Pain?

I am 18 years old, 5"9 and weigh 9 stone. The past few months i have been experiencing bad headaches and randumly feeling dizzy throughout the day. I also get really hot and feel as though my heart is beatin out my chest and every now and then get sharp shooting pains in my chest. I was on antidepressants for my depression but came off them about 2 months ago because i thought they may have been the cause of this but it hasnt went away. I still struggle to sleep at night, sometimes dont sleep at all yet i constantly feel tired and really weak at times aswell. No one seems to have any real answers. Could you help me please?