What Causes Rapid Weight Gain Despite A Normal Thyroid Report?

Im 29 now 170 5 1. I started going to the doctor due to rapid weight gain and anxiety attacks that i never had ( I was 130lbs) they checked my thyroid came back fine. in the mean time they had me on appidix even with that Im packing on the lbs. after 5 months of seeing this doctor and no results I started a detox. no carbs, no fats, no sugars, 500 cal a day. So my weight finally started going down im at 160 now after 13 days but now im noticing little white translucent strings in my stool. also during the start of my 500 cal detox I also started a colon cleanse that also was suppose to cleanse the liver the gallbladder the blood(full body cleanse.) not sure what it is or if it is all related. what type of natural treatment can i try if it is an issue?