The CoinInfo section at Cryptopia has a basic Explorer that shows which PhilosopherStone block it is on at any given moment.  This at least lets you know if you are on the same block as they are.  Since this is currently the only exchange where you can trade PHS I guess it should be the authority until a better Explorer has been re-established.

Note:  PHS is very weak now and unless more people begin actively staking this forking problem will occur again and again.  Please allow your PHS to split into a greater number of smaller sized blocks so that active staking can be in progress on a more consistent basis.