I would reccomend finding a myotherapist who can follow up with manual therapy after the injection. The cocktail that is injected should numb and deaden any pain and the specific muscles related to your referred pain can then be manually stretched and flushed of the lactic acid and other nociceptor pain chemicals which will restart the pain spasm pain cycle. I live in central Texas and I too am a chronic pain sufferer who has become a myotherapist specializing in drug free pain relief. Please find a REAL massage therapist who know the anatomy well and they will be able to help you. You may also be interested in a book called myofascial pain and dysfunction. It was authored by Janet Travell and David Simon. Awesome and Liberating. You don't have to hurt, there are other alternatives to phamaceutical and their side effects
www.myochanics.com