fasting

Dear people,

I have a few questions concerning Fasting; I attempted a Water Fasting on my own but I failed; I drank the wrong water (extremely high in calcium, I did not know)and I exercised too much. (yoga, walk and some push-ups) Not that much but apparently too much for my constitution. On the second day of the fast I experience sudden extreme weakness when walking my dog. After that I have trouble standing on my legs. I did not broke the fast but the next day I had so much trouble standing and got a hypoglycemia attack- but I think this was more due to dehydration- so I quit by eating a banana. Today I have still trouble standing but since taking a magnesium supplement it is remarkebly better. Now I want to fast again not making the mistakes I did. Not exercising, resting, drinking distilled water, maybe taking supplements before the fast. I am also going to look for someone who can supervise me if I can find this in my country.
Now my question is how long to I wait before I start again ?

I actually started fasting very impulsively because I was desperate because I had bad reactions to food and was afraid of eating so I thought why not try fasting but in my impulsiveness I did not educate myself enough and used bottled water. Will never do that again fasting on bottled water nor will I exercise.

I do want to start all over again quickly because I felt so much better mentally during the fast and I fed up living the way I feel. So how long to wait to not put myself in starvation mode.