Tightness and sore Hamstrings/legs

So I have been severely overweight, basically my whole life. The last 5 months I have been dieting and exercising. Anyway the last week or so upped my miles to about 6.5 a day. I always do light stretching before I get started. The last three days my hamstrings have been so tight. I have started doing more stretching and took today off. I’m just wondering did I just screw myself over?? How long does this last for anyone who’s had to deal with this?