The stretching as described above really helped me with a case of this a long time ago, but didn't help a recent really bad case I had, UNTIL I started doing it differently. The toes-on-a-curb method works great for the young and active with little pain, it's not as good for the decrepit.

Sit on a bed or floor, feet out and pointed up. Loop a stretch band or buckled belt around the ball area of one foot. LOCK YOUR KNEES, this is the key part. Pull gently until your foot comes forward as much as it will easily.   Then pull it in a little further, until you feel a strong stretch bordering on discomfort. If you still don't feel a strong stretch, raise the foot a few inches until you do. Hold 30 seconds at a time or as long as you can stand. Repeat a few times. Do it twice or 3 times a day or whatever you feel is helpful.

Other hard-won lessons:

At first if you have constant pain, stay in shoes with VERY thick, shock absorbing soles or springs.   As you get the pain to back off, switch to new, good shoes such as New Balance, that bend very well at the ball of the foot. Many of us who develop this condition do it because we are encased in stiff-soled boots or shoes that don't bend at the ball of the foot much, and your fascia really needs this to stay loose.

Also look into your gait; the root of my problem was having a 'cavus foot' which means I rode stiffly on the outside edge of my foot too much instead of rolling slightly inward with each step, from heel to toe, spreading the force across all five balls of the foot. Other people pound their heels too much. Your foot has its own problems. Check out what might be the root of the problem, otherwise it will just stay with you.