What is causing the fat pad on my upper back?

The cause may be hereditary or from steroid use.  I would recommend consulting with an endocrinologist before plastic surgery.

I would have to examine you.  If this is fat, liposuction can make a real difference.  Make sure that you select a board certified plastic surgeon performs
several hundred procedures each year, has several hundred positive
reviews, and has
hundreds of pictures on his website.Kenneth Hughes, MDLos Angeles, CA

 Fat deposits in the upper back and lower neck region are associated with Cushing's disease, protease inhibitors taken by HIV-positive individuals, and genetics. Treatment by liposuction is predictably good and often can be done with local anesthesia.

Photos can be helpful to evaluate this issue.  However a number of different conditions can lead to excess fat in the dorsocervical area. Its unlikely that your backpack did this.  An evaluation with a board certified plastic surgeon can help you find more answers. 

Without an examination, it is hard to give a cause for the fat pad. This may be due to certain medications, medical conditions, or just be a normal fat deposit. If you would like to see if it can be improved, see a plastic surgeon after seeing your primary doctor. 

Some people simply have more fat in the dorsocervical fat pad. Other times, the area can be enlarged as a side effect of medications.It is unusual for that area to cause pain if it's simply a fat deposit.You need to have this evaluated further if it's causing this much discomfort.If it is just a fat deposit, then it typically works very well for aesthetic reasons.Best of luck,Mats Hagstrom, M.D.