When I first started taking phentermine I had the same side effects as your having...the thightness in my chest really scarded me so I contacted my Dr she said this was normal and she watched my heart rate for a few weeks. Now all the side effects are gone except sometimes I have a hard time sleeping. Here's a website link that will tell you alot of the side effects of phentermine. Hope this helps!
http://www.phentermine.com/phentermine_overview4.htm