Q: Find my friends no longer accurate

I have been using find my friends for almost a year and it's been great.  However, over the last few days the accuracy has suddenly significantly decreased.  The location dot jumps around to various places and the program can't refine the location properly and so shows the probable location circle as covering the entire city in which I live.  I haven't changed any settings but the usefulness of the program has really changed almost from one day to the next.  Any help on this would be very much appreciated.  Thank you.