Sudden hypotension and tachycardia after exercise

hey , i am a 20 years old male , weight 100kg ,height 176cm , i have a problem with the exercise , every time i am on stress or exercise , my pressure suddenly goes down , with tachycardia, sweating ,nausea, and feeling that i am going to be unconscious in minute,  and fatigue !! and the attack remains for about 20 min to 1 hour , so what do you thing i have?

[CCFHeartMD17]

It is difficult to reach a concrete diagnosis via the Internet and the symptoms you experience might be caused by a benign cause like deconditioning but it is important to ensure that there is nothing else occurring that would cause concern.
I would recommend that you make an appointment to see your family doctor. Your doctor will be able to can sit down with you and take a thorough history (including a review of any medications or complementary therapies you may be using) and examine you.  If necessary , he/she can order a Holter test to have a closer look at your heart’s rhythm throughout a day or two. An exercise stress test to evaluate your heart’s blood supply in more detail might also be indicated once you have had your visit. Your doctor might also wish to check your thyroid function to ensure that this is normal.