I Fell From My Horse 13 Months Ago. Suffered A
It may be bleeding in the soft tissue.
Detailed Answer:
Hello and welcome to "Ask a Doctor " service.
I have read your query and here is my advice.
I saw the picture you uploaded and my opinion is that there may be intermittent small bleeding in the soft tissues as you lift weights.
This may happen due to rupture of small vessels that supply the muscles, tendons or skin of your back, or the bleeding may arise from the damaged vertebrae as well.
It is necessary to avoid heavy weights because intermittent bleeding may result in scar tissue or hematoma in that area, and examinations such ultrasound of the area and MRI may be necessary to understand better the condition.
Discuss with a spine Specialist for these issues.
Hope you found the answer helpful.
Let me know if I can assist you further.