I Am A Slight 70 Year Old Woman Who Was

I am a slight 70 year old woman who was diagnosed with IBS. I always had a great appetite but never was able to put on weight. Started having major IBS syptoms and just had a colonoscopy which confirmed the diagnosis. I am 5"1/2 inches and weighed 100 pounds but looked fine. Just before the colonoscopy I weighed myself and weighed and weighed 91/2. I always thought I was in good health but I am very concerned about my weight loss. Also I am lactose intolerant and believe that has gotten worse. Sugar was always good but was just tested with a 6 A1C. Thank you for any suggestions. Elaine in New York I am under a doctor's care and am not about to pay. Thank you.