It sounds as though you are experiencing anxiety attacks, brought on by your body's response to withdrawal. You've been to see a doctor, so you know you aren't suffering a heart attack. Some anxiety attacks can mimic a heart attack. Withdrawal can produce anxiety in its own ways.
You are reading your Bible and praying. This is a great step,
Boyce! Now, firmly believe that our Lord will not abandon you, and know that the pain, discomfort and anxiety are NOT forms of punishment from our Lord. (You already know this) Continue to read & study your Bible, and continue to pray. You are taking control of your body, after allowing spice to dictate matters, and it's not going to be an easy transition. But being clean is sooooo worth whatever comes your way. Our Lord loves you dearly. And for whatever it's worth, I am so thankful you have chosen to be clean. You are amazing!
For the times when the anxiety attacks are the strongest, read or recall to mind your favorite passage(s) of Scripture, and slowly speak it aloud. Offer this up in thanksgiving to our Lord, that His word provides you with strength and conviction. Then, slowly, repeat several times until you find yourself calming. You will find calm and relief. Our Lord truly does answer our prayers.
To your prayers, I add my own. And please let us here know your progression. We're here for you