I have a small red bump on my nipple. Its sore to touch and warm. Would you be able to tell me what this is.?

Breast Sore. Could be and most likely to be an infection, but either way should be examined by doctor to be properly evaluated and treated. There is a less common type of breast cancer known as Paget's Disease of Breast which though far less likely should be excluded.
Cyst, follicle. It sounds like this could be a small cyst or inflamed follicle. Don't try to squeeze it. Use some warm compresses and it should resolve. If it does not or if it gets larger and more painful see a doctor.