Learn from Mistakes
As with any major life change, managing a gluten-free life will involve some trial and error. This means you might ingest gluten by accident and have a negative response to it. In the worst-case situation, your symptoms may return for a day, a week, or even longer.
Unfortunately, once you've gone gluten-free, your body will be programmed to make a big deal out of even the little amount of gluten you eat. Most people (but not all) have a negative response to even minor quantities of cross-contamination. Learning your level of tolerance for gluten cross-contamination and what you can eat without having symptoms may take some time—probably months. It's easy to mentally blame yourself for your faults, especially if you're physically miserable. However, if you can, try to see them as a learning experience and focus on not making the same mistake repeatedly.