If your thyroid is in check, and your doing everything you said you are, then be pacient because nothing is wrong....Weight loss isn't linear...You won't loose the same every week and you will have stalls. Personality, I've had stalls that have lasted a month...But if your creating a defict calorie wise then the weight will eventually come off
Other factors could be masking it, such as water weight and bloat
20 pounds in two weeks is alot...give your body some time to catch up...Good luck
Quick question ...how long have you been stalled for, and are you sure your eating the proper amount of calories for your height, weight, and excerise level?