Fill Problems

I was banded 9 years ago. Last year I had a fill of 1/4 cc in April everything was fine until around the middle of May. I started to vomit unable to hold food down or fluids by June I was dehydrated week and unable to function. I went back to the doctor and he removed 3/4cc of the fluid from my band. In between July and January I receive 2 1/4cc of fill and was great. In February 2017 I received a 1/4cc at a weight of 175 seven days later I was 160 and dehydrated. Had to have the fluid removed. I am back into the doctor in a couple of days and am afraid to get a fill but I need one and I want to know what is wrong that my band seems to tighten up after a few days. I am going to just use protein shakes for about a week or two and see if that helps unless someone else has suggestions.

Thanks much.