How to treat dog's ACL sprain?

Rhodesian Ridgeback 101 lbs has been favoring front left paw/leg for about 2 months. About 3 weeks ago, our new vet said it should heal itself and just to try to keep him from jumping. She gave him a shot (anti-inflamatory drug) to help the healing along, but no advice about whether I could give him something (aspirin?) for the pain. It doesn't seem to be improving at all, but I am reluctant to take him back (and pay for the visit) so soon. Any suggestions?

Call your vet and explain what is going on. You should not have to go back, but your vet should have told you what to use for pain. Here's a good site on how to handle a recovering ACL sprain.http://www.agilityability.com/acl_recovery.htm