5 days, take a break for 5 days, eat good, crush lots of water and walk for miles. Repeat as necessary but understand that you should only feel weak/really tired on the 1-3rd day otherwise you need vitamins or drink more water. Good luck friend!
It’s not about how much “should” you go… it more about how much “can” you go.
(When I say ‘can’ I mean a combination of mentally, physically and biologically)
It would be wise to start with a 3-5 day fast, then after a few months recovery, try a 5-10 fast… continuing until you get to 15, 20 or even hardcore 30 days. (Depending on how much body fat you carry)
This is just concern for op. Leads into fasting.
Autoimmune like Ms? What kind of autoimmune disorder? /Besides mold allergy.
How severe is the allergy right now?
Have you moved or resolved mold problems? What kind of mold?
If you feel healthy enough to fast and your doctor is on board then it’s a go. Otherwise just be very careful and listen to your body. That does seem difficult after you described your present symptoms.
It’s helped you before and could definitely help again. Again, make sure you’re safe.
Keep up the balance hydration and electrolytes. Keep us updated OP.