Or alternatively is there a way to split the 5V into multiple connection points so I can run my LCD and my probe.
I've read that I can split it through a parallel circuit with any number of devices whose total draw is less than 1A so that I don't fry my components. Does that sound right?
As mentioned, you can split your 5V line along a breadboard/protoboard and then use some resistors to power both your LCD and pH probe.
Alternatively, you could always just write one pin high so that it's at 5V (less efficient).
As a side note, the Arduino can only provide 500 mA maximum. There are other restrictions on certain pins (i.e. total of X to Y can only be 200 mA, etc). The Arduino website has the specifications for these current draw limitations.