“Many people have pain in the base of their foot. This could be due to overuse of one of many different structures in your foot. Common examples are sesamoiditis (inflammation of structures surrounding two small bones under the big toe joint) and plantar fasciitis (overuse of a ligament-like structure that runs underneath the length of the foot).

Pain on standing first thing in the morning is a classic symptom of plantar fasciitis. It is one of the most common problems experienced by runners, accounting for about 10 per cent of running injuries. It is also common among middle-aged people, particularly if they are overweight. It often starts with low-grade pain in the arch or heel of the foot and can get worse over weeks or months.”

Better Health Channel (https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/feet-problems-and-treatments#bhc-content).