I Had A Cortisone Shot On My Distal Hamstring On

I had a cortisone shot on my distal hamstring on Thursday. My distal hamstring in the region of the semitendonosis has been hurting for 4 years or more. It does not like me to stand for long. I have been to see a few doctors and have had months of PT. Nerve test and muscle test were normal and injury to tendon had ben ruled out. I asked for a steroid injection 3 days ago, since then it has tightened up more rather than help me. What is happening?