Stretch for muscle tightness is most often the wrong decision.
Especially with an injury.
There are 4 basic reason you are tight so learn the difference and treat yourself better!
short vs long muscles (Pulled hamstring and Tight IT band /sciatica)
spasm at the spine (Hurts to get out of bed or take a deep breath)
electrolytes (charlie horses and calf cramps)
day after the gym
these all each have different responses and THEREFORE different treatments.