Feel like breaking my fast early cause I think it's pointless

I'm on day 10 of a planned 28 day Water Fast and I feel like breaking it because I don't think it will make any difference. My entire reason for fasting is to try and get rid of this awful brain fog that's been plaguing me for for the last 5 years. But in the past 3 months I've been on a 14 day Water Fast and a 10 day Water Fast and it did absolutely nothing for my brain fog. I just don't see why I should continue to put myself through such difficulty for no reason.