Step 4: Read and complete the decision guide to learn more about your symptoms.
From your answers, (mild ankle pain, no fever, for at least three weeks, with swelling and morning stiffness, but no other joint pain), a number of conditions come to mind.
An ankle sprain or tendonitis can cause pain and swelling, though prominent stiffness in the morning would be a bit unusual.
Ankle arthritis could cause this, and a number of specific disorders that commonly cause ankle arthritis are listed on the next page. If you have psoriasis, Crohn's disease, ulcerative colitis, or prominent low back pain, for example, conditions on the next page may be of particular importance to you.
Infection in the joint, including Lyme disease, is a possibility, though not as common as other possibilities.
There are other possibilities (if you can believe it!) and early treatment is important for many of these, so it is important that you see your doctor soon for evaluation.
If your ankle pain is already improving, you may just need to give it a bit more time; over-the-counter anti-inflammatory medicines (such as acetaminophen or ibuprofen) are reasonable to try unless you are already taking them or your doctor has told you to avoid these. If symptoms persist, see your doctor for evaluation.