Well, that could be a food sensitivity to any number of food families. While you were in Stage 1, were you eating any nightshades (potato, tomato, peppers of any kind, paprika, chili powder, eggplant)? Lip swelling is a common reaction to nightshade allergy/sensitivity. If you think that might be it, take all the nightshades out of your diet for at least 2 weeks (please Google to make sure I didn’t leave any out) and then test yourself with a small serving of one. If you’re okay, add more. Some people need to hit a certain amount before they get symptoms. If you’re able to eat quite a lot of these food a day or two into the test, and have no symptoms for 2-3 days, then the issue probably isn’t nightshades. Sorry, that’s about the best I can do. Hope it helps!