I'm having quite hard time to go through even the second day of my water fast. Left side of my chest feels 'weird', like a gentle dull pain inside and my heartbeat feels irregular. Is this normal or does this mean that my body is not handling the Water Fast at the moment?

Some history if it matters. I've been living quite unhealthy life for quite long including drugs, alcohol and bad eating habits. I've had similar problems with chest pain before when using drugs. Also recently I've had so bad stomach pains that I thought that I have to do something. I've been now on gluten and lactose free diet for few weeks and now I thought I should try fasting. I could handle the headaches, fatigue and dizziness, but the heart problems are bit too scary to just 'handle' without being sure these are normal part of healing.