I am glad to see that you are already working with your doctor
to develop a solution to your plantar fasciitis. As you know, plantar fasciitis is a condition in which the connective tissue in front of the heel bone becomes inflamed and irritated. This leads to pain in the foot especially when you stand for long periods of time or walk.
Fortunately, plantar fasciitis often does get better if you perform the stretching and strengthening exercises that your doctor introduced you to. Unfortunately, these exercises don't work right away. Often you need to do them daily for weeks to month in order to have maximal benefit. Physical therapy and anti inflammatory medications like ibuprofen can also be quite helpful.
Plantar fasciitis can become a chronic condition, mostly because things like fallen arches and over pronation of the foot predispose to it; therefore if you have these conditions, you will always be at risk of developing another attack. You can minimize this by wearing supportive footwear designed to prevent over pronation and by staying off your feet when able to do so.
Make sure to see with your primary care doctor
for more specific information!