Next to the major joints of the body are small sacs filled with thick fluid called bursa. These cover major bony protrusions into soft tissue, acting as shock absorbers between the two. The bursa are found next to the hip, shoulder, elbow, heel, and other areas. Either due to overuse, misuse, infection, or another pathology, this sac can be inflamed and lead to pain and tenderness. This begins as sharp pain, and usually evolves into a duller, aching pain.