I stretch enough before exercising and it still hurts. Running involved more injuries than most sports because it is weight bearing.
Proper equipment is essential for running, and that means sneakers.
Each type of athletic shoe has a specialization. Apparently this is true and not just sales hype. Spend what you need to in order to prevent or alleviate injuries. It seems possible that you might have attained your realistic weight already, and that those last few pounds may just be unrealistic for you. If you want to talk to someone further about any of this, there is a fitness trainer available a few hours a week at health services.