The hip handles force during almost every step, pivot, and change in position, so even a mild issue can start affecting the day in noticeable ways. Sometimes the source is inside the joint. In other cases, the discomfort comes from an irritated bursa, overloaded tendons, or tight muscles around the area that are working harder than they should.
Bursitis happens when one of the small fluid-filled sacs that helps reduce friction becomes inflamed. Once that tissue gets irritated, lying on that side, walking, longer outings, and stairs can become much harder to tolerate. Many people start compensating without thinking about it. They shorten their stride, shift away from the sore side, or tighten the glutes and outer thigh to protect it. Over time, those changes can make the issue harder to calm down.