Wife Has Had Symptoms Such As Muscle Soreness/stiffness, Coughing, And

Wife has had symptoms such as muscle soreness/stiffness, coughing, and fatigue since Tuesday. She woke Friday and could barely get out of bed. Her doctor, after taking a throat culture, diagnosed her with strep throat Friday and perscribed amoxycilin. She has been taking the antibiotic for 24 hours. She can still hardly get out of bed. She is very worried of rheumatic fever. Should we be concerned?