I sprained the muscles in my back (I think) from carrying heavy grocery shopping bags, 4 days ago (I am female). I felt mild pain initially afterwards both in my upper arms and mid-upper back. Since then although the pain in my arms has gone, the back pain is worse than ever - it is continuous and gets worse when I stretch or move. Even the pressure of sitting against the back of a chair or lying on my back is excruciating. I can't get away from the pain either through moving or resting. It is also very stiff that becomes worse throughout the day. I have tried ice, heat and sleeping on my side but nothing helps. The logical part of me says that it will heal and the pain and stiffness will disappear but I am so scared that it won't as it is so painful. My doctor couldn't find anything abnormal examining me. Does anyone have any idea how long it will take before it stops being painful? Please help. I am only 21.