Congratulations on already losing 50+ pounds ! That's fantastic ! Why isn't the weight coming off now ? Hard to say since we don't know anything about you or what you've been eating.
When it comes to weight loss, what matters most is what we eat. Good nutrition is what takes the weight off and keeps it off. Exercise is what keeps our bodies fit and healthy. Have you been logging your food choices ? If not, I'd recommend that you set up your Spark nutrition profile with your current information. Start logging your food again. Studies have shown that people who log their food choices lose more weight than those who don't.
You mentioned that you started running. It's possible that you're not eating enough. I know this is going to sound strange, but eating too little and exercising too much can hinder a person's weight loss, not help it. Women, in particular, are notorious for drastically cutting their caloric intake and increasing their workouts in hopes that that will speed up their weight loss. Well, as I mentioned earlier, that can hinder our weight loss not help it.
What to do ? Stick with it ! If you continue to eat right, watch your portions and get some regular exercise that includes some strength training, you will lose weight with time.
As you know, weight loss is a slow steady process. thus the need for patience.
One last point, if you are not doing any strength training, I'm going to encourage you to start. Add lean muscle. Muscle burns fat and the more lean muscle you carry, the more efficient your body will be at burning fat. don't worry, you will not look like a body builder if you lift a heavy weight. that is a misconception.
Women benefit from strength training just like men. So, don't neglect your strength. That extra lean muscle will help your body to become more efficient at burning fat. AND... the added lean muscle will help you to drop clothing sizes. Muscle is dense and takes up less space on the body than fat. As such, while you might not lose any weight, you could lose clothing sizes along with tightening up your body.