First of all, you didn't say you had any infectious diseases. If it is an acute infectious disease, such as influenza A and hepatitis A, it needs isolation treatment.

If it is hepatitis B, hepatitis C, etc. You don't need isolation, as long as your liver function is normal, you can go to school normally. It turned out to be bacillary dysentery. After it is cured, you can go to school. If you haven't recovered, you'd better rest at home for treatment. In addition, if you infect other students, you will feel guilty at that time, so don't listen to your mother and tell the teacher that you can go to school after you are cured. This is not criticizing your mother. It is selfish to do so, regardless of the health of yourself and your classmates.