Weight gain?

I have been yo yoing in weight, sometimes I'm up 2-4 lb in a day! I'm eating healthy, no gluten, very little dairy, lean meat, portion controlled everything, no sauces, very little sugar/alcohol. Then if I have one glass of wine or one serving of ice cream my weight goes up. Does this happen to anyone else? I was working out regularly and stopped for about two weeks due to getting sick. I know I need to start exercising again and plan to starting tomorrow. Definitely aware that diet AND exercise = weight loss ...but it's just crazy how fast my weight goes up. I'm 179 lb and a few days ago I was 175. :( 
Any ideas on what the cause is? Or share similar experiences