Adam, lots of recommendations from folks, but I don't think any are qualified to prescribe anything to you (even if one is a doctor...because they haven't examined you)...but, they all do have your best interest at heart. So, here comes some more information from a non-qualified person.
I'm sure other things can cause it, but your mention of needing to have a bowel movement worries me. My mother and I carried my father to a doctor because of chest pains he was having...doc did a quick EKG and called an ambulance for him. While waiting my father said he had to have a bowel movement...the doctor frowned when he heard him say this. I had to stand guard with him while he *tried* "to go". He eventually left the hospital 44 days later in a body bag. A few years later a customer of mine was missing his main worker (tire business), nobody new where he had gone. Finally, at closing time someone peeked into the warehouse bathroom to turn the light out....there sat the missing guy dead on the toilet from a heart attack.
My sister just had a coronary computed tomography angiogram, or CTA for short. This is mostly a non-invasive test, an IV is connected for the contrast dye to be administered. The test takes probably 1/2 half hour compared to several hours for a heart cath. My sister paid $780 for the test and it took a load of worry off her shoulders when she got a good report. You would want to have blood work done beforehand to be sure of general chemical/organic body conditions....the dye used in the test could wipe out weak kidneys (my brother was a transplant recipient and my mother on dialysis the last years of her life...she found out she had kidney failure when she was about to have a heart cath!).
Here's a link to a description of a CTA, the article is clinic specific but gives a good overview of the test: http://my.clevelandclinic.org/heart/...ronarycta.aspx
Best wishes, Adam, take care of yourself so you can continue to take care of those you love.
PS One more link to a CTA article...on WebMD: http://www.webmd.com/a-to-z-guides/c...m-ct-angiogram