Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency help after a serious injury if a limb looks bent or out of place, bone is visible through a wound, bleeding will not stop, or the area beyond the injury becomes pale, cold, numb, or weak.
Sudden severe pain with an inability to stand or use the limb also needs urgent assessment.
Arrange same-day care if you have fever with a painful area over a bone that is red, warm, or swollen.
Seek prompt care if pain is rapidly worsening, you feel seriously unwell, or a child will not use an arm or leg.
And for anyone, someone who:
Book a routine appointment if unexplained pain lasts several days, keeps returning, or gradually worsens.
Also seek assessment if pain repeatedly wakes you, a lump or persistent swelling develops, or you have unexplained weight loss or marked tiredness.
Every sign above is quoted from the sofidex article on Bone pain or tenderness. If you are not sure, err upward — it is always reasonable to be checked.