Feels as though your heart will jump out of your chest/flutters/is irregular in beat/gives you panicky feelings.
Likely at the very least a massive Vitamin B 12 depletion – please see more here.
Possible high thyroid function.
Caffeine and other stimulants consumed in error(do not settle you down)
Avoid all self medicating – caffeine/alcohol will only make this so much worse.
Ensure that your Vit D levels are really high as maybe without enough you are not absorbing the magnesium and other minerals needed to keep you well.
Use Vit B, Vit C and more nutrient dense foods, esp more fat and protein to rebuild you. Heaps more coloured veggies, to provide minerals.
See an acupuncturist/Chinese herbalist to help rebuild your Blood energy