My periods problem can some body tell me why i am getting this problem.?

I am 33yr old.I always have a irregular period. This week i got my periods for 4days and on the 5th day i didn't have a bleeding but in the night time i got bleeding again it never happend before. I think i drank hot coffee just before that. I don't drink coffee everyday. Can it be the cause for bleeding again? i had a abortion 2months before . Is that a cause for this abnormality?