It is normal to have discomfort for a day or two after braces or retainers are adjusted, which can make eating uncomfortable.  Discomfort is both normal and temporary.  Soft foods are a good solution for a day or two.  You can also take non-prescription pain relievers such as you would take for a headache.  Ibuprofen has been shown to work the best, but always check with your physician prior to taking medications you are unsure about.