If you cannot pinpoint it, your right it's time to check in with the doctor. It could be nothing, but its better to be safe. Sometimes, your body will naturally hit a plateau. You just have to keep slugging away and making all the right choices, eventually it will cry Uncle and reward you with more weight loss. Also, remember that muscle weighs more than fat. So, that could be another reason you aren't seeing a big change on the scale. I hope you feel better!