Brief Answer:
Might be gout; trauma and cellulitis to be ruled out

Detailed Answer:
Hello.
Welcome to HCM.
This is Dr. Swarnava Dattagupta answering your query.

I understand your concern.
You have provided a very short history. So I would ask some questions to understand your problem better-
Any history of trauma?
Any swelling in other ankle or foot?
What medications do you take?
Any local redness pain or fever?
Do you have diabetes or hypertension?
Any previous history of arthritis or pain in other joints?

Kindly answer the above so that I can help you further.
As of now it seems like gout or other forms of arthritis as the swelling is unilateral. Chances of cellulitis and trauma should be ruled out too.
Also swelling of other ankle and foot should be ruled out as bilateral swelling is more common and can be due to heart or kidney problems, uncontrolled hypertension etc.
Avoiding prolonged walking or dangling legs and keeping leg elevated will be helpful. Also hot dry compression and simple ankle drills are advised.
Get blood test for complete blood count, ESR, CRP, blood sugar and uric acid done.

Kindly get back with the answers and preferably the test reports.

Hope I have answered your query.
Consult me for any further questions.
Regards.

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Brief Answer:
Might be due to arthritis; get the tests done

Detailed Answer:
Hello.
Sorry for the late reply.
As the swelling is unilateral and you have history of arthritis, it is probably the cause here. However, other causes are still to be ruled out and hence I would suggest you to get the investigations done as mentioned above.
If the swelling is on both limbs, hypertension may play a part and get your blood pressure monitored in that case.
Follow as advised before for the management. For pain, you can continue pain medications.
Kindly get back with the reports for followup.

Wish you good health.
Regards.

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