Based on the information, it does not look like caused by plantar fasciitis, as the location of pain and nature of presentation is not typical for it. Presence of localized swelling, tenderness and aggravation by walking or bike is suggestive of some localized pathology. There are many possible causes, which can present with similar symptoms some of them are trauma, ligaments sprain, muscle strain or micro-trauma injuries which can be caused by running on uneven surfaces, surfaces that are too hard or too soft, or shoes that have poor force-absorption qualities or fit incorrectly. Repeated over stressing of the same structure of the foot may cause stress fractures, tendonitis, plantar fasciitis, and acute and chronic osteoarthritis, which can cause foot pain. Even injury to plantar fascia can cause arch pain. As you are having it for the last 6 months without any self recovery, I would strongly consider proper evaluation and investigation to find out the exact cause, which can be treated effectively to get rid of this pain. You need x ray and possibility MRI of foot and arch, to pin point the diagnosis. In the mean time, I recommend taking rest, warm compression, foot elevation, pain meds local/oral and avoid or cut down long walk and bicycle.