Now I'm obviously not a doctor, but your symptoms, particularly the chest pains, might just be anxiety like a few others mentioned.
Several years ago I got done workin out, came home and showered, smoked a blunt, and started playin Halo 3 just like I did every day. So I'm sittin there playin and all of a sudden my heart started beating really fast, I was sweating, my throat felt really tight like it was getting harder to breathe, and I seriously thought I was about to have a heart attack.
I was freakin out so I went and laid down to see if it would go away, and after what seemed like a few hours, I started to relax and went to sleep. I woke up the next day and felt fine. My first thought was that I was over-stimulated because I used to take that nitric oxide shit before I worked out. So I stopped taking it.
The next day I followed the same routine except I didn't take the N.O. before my workout. I smoked a blunt, fired up Halo 3, and the rapid heartbeat came back again. At this point I thought it was the weed doin it to me, so I quit that for a while. I also made a Dr. appointment to get it checked out. They did their EKG test and what not and said I was fine and diagnosed me with anxiety and put me on Zoloft.
After those episodes, I started noticing sharp shooting pains in my chest and head every few days or so. Again, the doctors attributed these to the anxiety.
So to shorten this story up, to this day I still have the anxiety. The panic attacks aren't nearly as frequent as they used to be, but I do still get them and I notice the other weird pains in my chest and head too. When I take my Zoloft, most of it goes away.
Now while my symptoms are obviously a bit different than yours, I think it just goes to show that anxiety can definitely cause your body to do some weird things. At first I was convinced that the anxiety diagnosis was all bullshit and I had something serious wrong with me, but now I see that it probably was causing my problems after all.
Since it sounds like you're at a point in your life where you're really stressed out about a lot of things and you have a lot on your mind, I think it's possible that the stress is what's causing your symptoms.
Again, I'm not a doctor, but since I had (somewhat) similar issues myself, I figured I'd let you know that it might not be all that serious even though I'm sure it feels like it is.
I hope everything works out for you man. Definitely get your health fixed though before you stress out even more over IM because IM can be extremely frustrating at times.