Hi, I Am 38 Year Old. Last Month I Had

Hi, I am 38 year old. Last month I had my period on 12-19-2015. This month, about 3 days back I had a little bleeding. I thought it's a regular period but i guess it was not. After that there is no more bleeding. I know I am not pregnant. I have no pain or no other problem. I am just worried what is that? Can you pls help