My Brother, 5 months ago he was bitten by a spider he thinks, or a Doctor said. He was given a high dose of Antibiotics and the spider bite got better. I found out today, he has very loose stools actually he just water comes out. Once or twice in the morning. This has been going on for 5 months. He says he has spoken to Doctors and is making appointments. His blood tests are fine, and he is going to have a upper and lower GI. Is there something else going on, because he never would tell me this.