Hi there, rest after an injury will really depend on the severity of the problem. The fact that you have injured your muscle so soon after the initial strain would seem to me to suggest that you have been doing a little too much during your 'rest' period. Stretching and walking are all very good ways to support the body in its recovery but they can still be problematic if we do too much.
I would suggest cutting down the length of your walks and, since this is a reoccurring problem, try and make an appointment with a physiotherapist (many of these clinics are up and running now). They'll be able to give you specific exercises to guide your recovery.
If you have any pain, try applying a little Atrogel Arnica Gel to the area as well.
When you are ready to get back to running, gradually increase the length of your runs instead of trying to get back to your previous distance straight away. Warm-ups and cool downs are also very important for preventing further injury.
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