What Causes Tiredness Along With Rapid Heart Rate While Smoking Meth?

hi doctor im a 20 years old boy, i started smoking crystal meth two weeks ago but the past week i did it alot i even sleep a night nd sleep the next night, i haven't eaten for 3 days i just take bites but now i through all the stuff away before i get into it, it is getting so addictive, when ever i have an event or stressed it was always my friend, i can over come it, not the problem. but the prob is my body i feel so tired for a single action nd feeling lost, will my body be ok and how long will it take to clean off ( estimated, been smoking for 2 weeks regularly)?? and will everything get back to normal this fast??.
Moreover, im loosing my mind every morning. i just feel tired, thats all no marks or anything and when i lay down in bed to sleep my heart beats fast suddenly for a while till i forget about it then its normal. is there anything else i can do for sleeping, the last i smoked was 3 hours ago nd no more. threw everything away!!