This could be related to many things. Throwing Z into the mix makes everything more difficult to track.
First - based on the fact that you were underweight I would guess that it is impossible for you to be more than 'medium' sized. Based on that - your current weight of 220 on a 6'2" body is obviously too much. 180-190 may be more in line.
Z is so tough to get off of. See if you can pick up a copy of the current 'SELF' magazine - there is a great article on the difficulties of getting off of anti-anxiety and anti-depressants. Unfortunately the article is not online. Some of the jolt symptoms are very similar to what is in the article.
As an aside - I am not a fan of coral calcium. If I need to get calcium into a diet I prefer carrot juice, mollasses, or calc-t from www.herbsfirst.com
I also would certainly see a cardiologist - if nothing then just for the diagnosis. But the Z again can really skew things. Here is an article to help put that into perspective.
Finally, in the short term - make sure your diet is clean with plenty of organic fruit, veges, whole grains, nuts and seeds. Raw garlic, plenty of water, and superfood. http://superfood.andmuchmore.com