After the re-feed

So to start with I've been on a two week juice fast that led into a 30 day water fast, that is back primarily on juice again. This is all to fight a long term infection that I feel I haven't quite bested but close.

My BMI is 13, so I'm pretty low and looking like someone could hang me up for Halloween, but I don't wanna give up the fast. If I were to re-feed, how soon could I fast more? I'm determined to beat this but I dont want to do permanent damage to my body.

What would be a good protocol to follow to finish this out and get a clean bill of health. I saved time and money from work just to do this and I wanna make sure I see it to the end.