Brief Answer:
Cause could be plantar fasciitis.

Detailed Answer:
Hello,
Thanks for your query.

From your symptoms, it seems that you are suffering from plantar fasciitis. It happens due to inflammation of the plantar fascia.
It hurts the most with the first few steps in the morning because the plantar fascia is tight and has not stretched out yet, and throughout the day it loosens up. The best thing you can do is when you wake up in the morning, before getting out of bed and taking a step, give yourself a little foot rub.

There are many things you can try to help your foot get better:

Give your feet a rest. Cut back on activities that make your feet hurt. Try not to walk or run on hard surfaces.

Use shoes with good arch support and a cushioned sole.

Do toe stretches, calf stretches and towel stretches several times a day, especially when you first get up in the morning.

To help the pain, ice the area immediately after getting up in the morning. You can use either a store-bought cold pack or a frozen wet towel. Ice for 10 or 15 minutes. To reduce inflammation, take an aspirin or ibuprofen at mealtime.
A 4-inch wide Crepe bandage wrapped around the region also helps reduce discomfort.
Consider using soft silicone heel cushions for preventing any further damage to fascia.
If the pain is not responding to these modalities even after 6 weeks, a local steroid injection at the site might be helpful in relieving the pain.

I do hope that you have found something helpful and I will be glad to answer any further query.
Take care

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