Painful Spots on Back of young teenage girl

Patient: Hello, I am a young female teenager, I have bad spots on my back, which get on my nerves day to day. I wouldn’t know whether to call it acne or not, but there are many of them. Some are not painful at all but some of them are extremely painful. I don’t get spots on my face at all just on my back. I have also noticed I haven’t had any periods for the last few months. I have only started generally getting these spots after my periods started in June 2014. They are becoming more annoying by the day. My back also feels greasy even after getting in the shower. Is there anything that can be done about this?

Symptoms: Greasy feeling to back, not having regular periods, painful spots