I'm worried about my mom. She's been unwell since April 15th. Initially, she had fever, vomiting, and headache for two days. Now she's really weak and has a dry cough, mostly at night, making it hard for her to sleep. Even after taking antibiotics, the cough isn't going away, and medicines are making her feel nauseous. Her oxygen levels are fine, but I'm still concerned about the ongoing cough and sleepless nights. What could be causing this, and what should we do next?