I have learned that those shots don't work if the shot is not injected into the exact nerve site.
I've had them 2 and 3 weeks apart. They didn't work and a year later tried again having 3 injections 3 weeks apart. STILL didn't help!
You'll have to check with your Pain Man. Doc to find out how much and how often for your case.
This depends on the area of the body, the dosage, and the reaction of the body to the shot and how good the doc is that is giving the shot. Some people get the shots and have no further problems for years, others don't work longer than a day or two. If you have the injections and they don't work for longer than a week, then they aren't working for you. Try something else. good luck