I sprained my ankle. it's swollen/painful but appears to be moderate. the x-ray confirmed sprain. the doc ordered a backslab. is that overdoing it?

No: By 'backslab' I am assuming you mean a posterior splint. This is appropriate for a week- 10 days after a significant sprain although a 'walking boot' may be more comfortable and as effective.Aggressive , early rehabilitation after ankle sprains is becoming more popular among orthopedic surgeons and appears to be 'better' at returning patients to their pre- injury status more rapidly . Best of luck.

Immobilization.: Splints, casts, braces, and use of crutches are some possible ways to minimize pressures on the ankle.