The phrase "feel rotten" is commonly used to describe someone who is feeling terrible, physically or emotionally. However, there are several synonyms that can be used to convey this same feeling, such as "feel awful," "feel sick," "feel lousy," "feel miserable," or "feel wretched." These words can be used interchangeably, and each conveys a sense of discomfort or suffering. Whether someone is experiencing physical pain or emotional distress, these synonyms can help describe the depth of their suffering and provide empathy and support. Ultimately, finding the right words to express one's feelings can help to alleviate some of their pain and discomfort.