Because I haven't actually seen it, there are many reasons, which may be insufficient warm-up, or the action in that place is not in place. It is recommended to go to the hospital for examination. Joint problems can be big or small.

Rest, of course. Generally, in the process of fitness, if you find that you are unwell, don't insist. Before continuing to exercise, you must keep your body in the best condition. There are two reasons. First, if you continue to exercise under the condition of physical discomfort, you may be hurt more seriously. Second, if you are unwell, then your movements will overcome the strength to control the uncomfortable parts, then your movements will be nonstandard, and the nonstandard movements will not achieve the desired effect. In particular, heavy weight training must be carried out in good physical condition.