Pain at the bottom of the left breast could be caused by a wide range of reasons.From what you describe,this doesn't sound like breast cancer to me,especially at your age and also because this disease is almost never associated with breast pain..
I don’t think your problem is related to a breast condition.but it could be due to several things. For example,Costochondritis, (chest wall inflammation) flatulence,ulcer,angina, pulled muscle,acid reflux, stomach inflammation etc...All these symptoms could cause the discomfort you are describing.
If this pain does not go away and particularly because you have an enlarged spleen, I would advise you to consult your doctor to conduct a physical examination and various diagnostic procedures to zero in on the underlying cause.
Thank you for the answer! I have an appointment with my doctor the 11th of November. If it gets any worse Im going to try and get the appointment earlier. Again thank you for answering my question. It worries me a lot that it came out of no where.