Breakthrough bleeding, fake period, pregnancy likelihood...advice please?

Hi everyone just abit of advice needed will be greatly appreciated as fairly confused right now! Basically i finished my first pill pack, had a 7day break, and then started back on my second pack. When i started back this was last sunday and the previous night(Saturday 15th?) i had just finished my period. I continued to take my pill for a few days but stupidly forgot to take it for 4 days, and had unprotected during this time. Just Monday there, a week after finishing my period, it seemed like i was hit with another! I realise it cant be my period though as i only just finished it a week ago? It cant surely come back that quickly? It is heavier than my normal periods, and has went from bright red to dark, i'm on day two of this heavy flow now and it doesnt seem to be going anywhere! I'm also experiencing cramp which i dont even normally have during periods. Could this, despite being heavy etc, be breakthrough bleeding? If so is there still a possibility i could be pregnant? (Have heard differing opinions on wether or not you can have breakthrough bleeding and still be pregnant) Any info would be greatly appreciated, just joined yahoo so bear with me! Thank's :)