Not everyone experiences die-off; if your kidneys and liver are in good shape, you won’t experience any die-off symptoms (flu like symptoms).
I would eat food asap because you definitely need to eat to survive. We have a strict forum foods list that many forum members follow; if you are interested in a link to it, email able900.
The headache is a die-off symptom BTW, so it sounds like you experienced some.
You could have something similar to candida such as h.pylori, SIBO (small intestinal bacteria overgrowth), or parasites, but the white tongue is an indication of poor health and oral thrush.