A 42-year-old female patient is complaining of a sudden onset of dizziness that started while at rest and is constant but not worsening with a change in position. She has been on bed rest for the past 2 weeks after an infection to her incision for a total knee replacement. Her vital signs are HR: 108; RR: 24; SpO2: 91% (on 15 LPM O2 via mask); BP: 132/88. Her lung sounds are clear in all fields and equal bilaterally. Her skin color and temperature are unremarkable. She has not passed out, and her blood sugar is within normal limits.Based on the assessment information given, select the most likely condition this patient is experiencing.