Question regarding my health, Ive had some weird *** symptoms and i wanna know what you think?

Okay right so let me tell you about myself, Im 18, 176 pounds, 6 feet tall and a guy. So for the past weekish ive been feeling random increase in heart rate and my resting heart rate has went up on average, not by too much though. However sometimes during the day maybe twice Ill get this feeling of fatigue and my heart beat goes up and i get a little short on breath possibly a little dizzy but not too bad. I work out like a madman and lift all the time but for the past week the only thing ive been able to do is distance run otherwise my heart rate goes up so much and I feel all weak and fatigued. Weights that I lift all the time have been feeling heavier as well i think just due to the fatigue when my heart beat goes that fast. But it happens sometimes when im just sitting down like calmly talking to someone. I've never had anxiety attacks and its not like im getting nervous or strssed when it happens. The only change ive made in my diet in the past month is taking a multivitamin and iodine supplements at very low dosages to help with general health. However I had been taking both those for a while before any of this started. I've done some research and one of the big things that came up because im not sick or ill or anything and have no diseases or viruses was hyperthyroidism, however I have no neck pain, the other symptoms point towards this. Let me know what you think especially if your a doctor or have good medical knowledge or have felt the same way.