Day 4 of water only fast - Chest Pains

Hi everyone. I'm new to the forum, but over the years I have frequented it to read posts by others.
I am currently on day 4 of a water only fast. Until this morning, everything was going well. This morning, though, I had to walk up a flight of stairs...only about 14 stairs...and immediately when I got to the top my heart was pounding and I had discomfort in my chest. It is now 6 hours later, and I am still having discomfort and pain in my chest...but not on the left side, directly in the middle of it. It feels a bit tight, uncomfortable, and aches.
A bit about me so you can advise me better, I am 28 years old and overweight, but I have not been overweight for very long. I put the weight on during the past year, pretty quickly, and prior to that was always a healthy weight. I suffered a severe loss last year, became depressed, and began eating emotionally and drinking alcohol frequently...causing me to pack on the pounds. That was the reason for this water fast, not only for weight loss, but mainly to undo my horrible habits and cleanse my body of all of the toxins I have been flooding it with in the form of alcohol, nicotine, and fast food. I have done Water Fasts in the past, the longest was 14 days. In the past, though, I was never as toxic as I am now. I didn't smoke, I rarely drank, and I rarely ate junk food.
So I am wondering if anyone has experienced chest pain like this? Should I end my fast? I considered a potassium deficiency, but this is only the 4th day of my fast.
Please advise me, because I am a bit of a hypochondriac and this happening has all types of scenarios running through my head, including just spontaneously dropping dead. So if anyone has experienced this, please let me know. I really do not want to give up on this water fast, but if no one has experienced this...and you don't think that it is just a detox symptom, etc ( I know for a fact that I am extremely toxic..alcohol 5 nights a week, pack of cigarettes a day, fast food every day for the past year)...then I will probably end this fast on day 4..eat a few days raw, and then perhaps begin a juice fast...? Please give me your opinions. Thank you!