(Concern) My heel pain has worsened. Is it a symptom of plantar fasciitis?

Since I started exercising, I try to walk properly on the treadmill at a brisk pace with the maximum incline, aiming for 10,000 steps. However, at some point, I began to feel pain in my heels when I wake up and take my first step, and even when I sit on the sofa and then step down for the first time, I experience pain.

Is this a symptom of plantar fasciitis?

When I actually walk 10,000 steps or start exercising on the treadmill, I don't feel any pain and think it's okay, but when I rest or wake up, the pain keeps coming back. They say I shouldn't leave plantar fasciitis untreated, so I'm worried. I think I should prevent it before it gets worse. I usually wear comfortable sneakers with cushioning for exercise.

Please recommend any prevention or treatment methods if you have any suggestions.