My mother has breathing problems even after 20 days of testing COVID-positive. Why?

Hi doctor,

My mother has a breathing issue, high CRP, and D-dimer. She was tested COVID-positive 20 days before. She also has a low SPO2 level. She is 61 years old and a sugar patient. She does not have any allergic reactions to medicines. She is comfortable eating and talking. Her fever has gone down for 12 days. She does not have throat pain. She is under the following medications such as Injection of Meropenem thrice daily, Injection of Tragocid once daily, Injection of Methylprednisolone 40 mg thrice daily, Injection of Emeset twice daily, Injection of Pantop twice daily, Tablet Xarelto, Tablet Vitamin-C, Tablet Zinc and Tablet Allegra M. There is improvement in external health, but still, she is facing breathing issues. Sugar level, BP, and pulse rate are normal. We have got her HRCT, blood test, and X-ray done. Please guide me.

Hi doctor,

Thank you. Her D-dimer is 12 mg/dL. I want to know if there is a risk of heart disease on such a high level. I am attaching the X-ray for your reference. Please guide me.