I hear ya about being so frustrated with this dr. It happens more than you realize. It sounds to me like you have a pain mgt dr that is in to injections only and some of them are that way and either prescribe no medication or give little.
What about about getting a second opinion with another pain mgt but make sure this one does give medication. This is something you can handle with a phone call and ask before scheduling an appt. Hate to say it, but he is probably right about seeing an orthopedic for your back. If your MRI is totally normal an ortho sure isn't going to give meds, they don't usually write nothing but Lortab anyway and nothing else. They don't want to get caught up into writing strong meds to patients and have to deal with the DEA ooking over their shoulder. These guys rather spend their time in the operating room than messing with the DEA.
I would say this but its your choice. Get the MRI done on your knee. You can have all sorts of things wrong with that knee that will show up on the MRI. It can be anything from a tear of the meniscus to ACL problems, so get him to at least do that. If you have some problems going on in there then no, injections will not help, could be a problem that requires arthroscopic surgery. ometimes, drs will go in & scope a knee to take a look to see whats going on even if nothing is showing on the MRI.
As for your back problems, if its an actual sprain they can be boogers to recover from. Each person is so different when it comes to pain problems. What kind of injections excatly ids he proposing on your back? There ane many different ones. Sorry I am not of much help but I did want to respond to your post. Susie