I’ve had plantar fasciitis twice - both times from energetic exercise. Neither time did it take more than a week before I was walking with relative ease again, but I saw a phyla day took advice about a series of simple exercises and strategies.
You need to see a physiotherapist as it’s not really what doctors are good at. You need to have a physio look at what’s causing the PF. it’s often to do with tightness in the calf and the way the muscles and tendons insert into the heel - so see if a series of careful but targeted calf stretches helps.
Also, freeze an almost full water bottle and then use it as a foot roller for about 10-15 minutes. The foot rolling is good anyway, and the icing of the soft tissue seems to help.
Lots and lots of stretches is what I did and still do: calf stretches, heel drops, and hip flexor stretches seem to keep my legs in balance.
I also find that walking barefoot as much as possible, and walking mindfully - really rolling through my feet and using all the foot
muscles consciously really helps. But I’m dance/ballet trained so probably more conscious of my feet and my posture and alignment than normal people.
What you start to work out is that the body is a whole system and so if one thing goes wrong, it’s usually connected in some way to the whole body - it may be that you gave some issues of alignment or posture which have found their expression in your feet.
Also, when I wear shoes - well-made and supportive shoes: NOT ugg boots or flimsy ballerina style flats. And I don’t think trainers are particularly good for your feet all the time, either.
When it’s acute PF is very painful. But that shouldn’t last for more than a week, particularly if you’ve been a very active person. With the right physical therapy you should be able to learn how to deal with it. It shouldn’t stop you running and moving for so long!