What Causes Delay In Periods,loss Of Appetite And Bloating After Eating?

Hi, Im 19 years old and very worried. I am about a month late with my period. My last one lasted like 2 weeks and was just extremely light, very unsusal for me. I am experienceing extreme bloating after eating, and i hardly have an appetite anymore. Today was the symptom that really freaked me out. I was outside for a soccer game and it was rather cold outside but i got stabbing pains in my breasts which has never happened before. Any advice?