What is wrong with me??!! Please help!?

I am a a teen girl. On friday my stomach began to hurt. I was taking prednisone prescribed to me and it was listed as a side effect. I ignored it and ate normally as I would. I then had sushi from a place i had never had it from. My stomach then continued to hurt and I developed diarrhea. I couldn't sleep friday night. All of saturday I had frequent visits to the bathroom and sat on the couch all day. On sunday the same happened but the stool became more watery and appeared mucusy. At a point I saw specks of blood! Right now i go into the bathroom and nothing come out except for the gross watery mucus. :O Im freaking out should i tell my mom? If so how? Are these normal symptoms of diarrhea? On Sat. i ate and drank almost nothing. On sunday i had a sandwich and that went fine. today I've had crackers 3 glasses of water a sandwich and a cup of cereal. What disease do I have? Is this just a reaction to the sushi i ate? Please help i need to better by tomorrow i have soccer camp that we already paid for. I am getting tired of this I have been home since friday :( so far this summer stinks. this is a serious question easy 10 points i know a lot of questions but I'm really worried! Please help. Thanks.