What Causes Pain In Hamstring Muscle After Taking Nerve Block Injection?

I recently had surgery to repair my Achilles tendon (approx 3-4 weeks ago). My injury seems to feel fine but I am having severe cramps in my lower hamstring, calf muscle and shooting pains in my foot. The pain in my hamstring seems to be originating in the area of where I received a nerve block injection. Are these affects associated with this injection? Thanks.