we spend a lot of time on our feet and the weight of our bodies and the strain of walking can certainly cause inflammation of the tendons or muscles. since you do not recall an injury this may be a strain. nsaids like motrin advil or aleve may help (assuming you can medically take this class of anti-inflammatory medication) along with some hot soaks but if your symptoms persist you will need to consult your medical provider for a proper examination and diagnosis.
i woke up this morning with what seems to be a sprained ankle i didn't hurt it the previous day what could be the cause