help me please. I'm so scared

I haven't breastfed my kid in nine months. My milk supply had completely gone away. When I squeezed my nipples today ALOT of milk came out. I had my period two weeks ago. It was normal. My breasts have been a bit swollen and I have a headache almost everyday for the whole day. What could it be? I'm really worried. I'm going to the doctor soon I just would like some insight.