Alarmist scenario: Rheumatoid arthritis or lupus.
More likely cause: Says rheumatologist Patience White, the chief public health officer for the Arthritis Foundation, “There are three main possibilities: osteoarthritis, which is related to age and injuries; an overuse injury, like bursitis, tendinitis, or ligament pain; and referred pain, meaning you have a problem in a place [say, your back] other than the joint that hurts—perhaps your knee.”
Reality check: Rheumatoid arthritis and lupus disproportionately affect women but are still relatively rare.
Rx: Rest and take an over-the-counter anti-inflammatory medication, such as naproxen or ibuprofen. An aspirin cream, such as Aspercreme, can also soothe sore joints. If the pain lasts for more than five days, if you have a fever, or if you feel extreme or prolonged fatigue, see a doctor.