Weight gain for No reason !!!!

Well.. not sure where to start... I went to the Dr. for my yearly paps.. everything came back fine.. he did blood work.. I got this really bad cold 2 weeks later went back to the Drs.. and he brought it to my attention that I have gained 4 lbs in 2 weeks.. I dont understand it.. my eating habits have not changed.. I am more active then I have been in a long time. The Dr told me to stay away from Salt.. and when I go back in for my recheck.. If I am still gaining.. He wants to run some tests.. my thyroid is fine.. my sugar was fine. I am very worried about this.. I am now weighing 150.
I dont feel good at this weight.. and was wondering if someone could let me know what just might be happening..
I am only hoping and praying its nothing serious..
Please help...

[Machelle Seibel, MD]

A. Gaining weight in a short time can be the start of a weight gaining period or it might just be fluid retention. If you continue to gain weight, make a conscious effort to watch what you eat and mark it down in a diary after each meal.  After a week or two, you can meet with a nutritionist and see if your choices of foods, amounts of food and time of day of your meals are contributing to weight gain.  Everyone