I Just Found Out That I Have A Goiter From

I just found out that I have a goiter from an ultrasound I had back in August. Should I be concerned about it or does it hurt to let it stay there? I am experiencing swelling of the feet and ankles and other parts of the body making it painful to walk, get up and down etc. I have developed a chronic cough since about December of last year, it is virtually impossible to loose weight unless I starve myself and eat only one small meal a day. I am on thyroid at the moment but am not sure if I should be worried.