I Am A 58 Years Old Postmenapausal Woman. I Had

I am a 58 years old postmenapausal woman. I had 2 c sections and then a laparoscopic partial hysterectomy at 42. I have always been slim and petit and in shape. I just gained unexpected and unexplainable weight after my bilateral salpingo oophorectomy on June 9th,2015--I feel miserable! My breasts feel heavy and my stomach is bloated and feel swollen every time I eat. Is this NORMAL??? I take gas -x it helps, but the weight??? --- I started yoga and walking last week. My question is, how long does it take to recover and go back to feeling normal after surgery? Does the weight go down after a while, or never???