Labor starting

Singleton
So for the past four hours I've been cramping like pain sometimes really sharp. I know this is the beginning Of something but I can't time any contractions really. It's pretty much constant until I get a sharp spike. I've walked, and fell asleep once but it's pretty consistent this time around. 
Tmi: also using the bathroom pretty frequently. 
Any advice on what's happening or what is the next step. Also a friend told me to try the castor oil thing to Jump my labor and contractions ( already know the safe way to do it) but I have never heard of doing that after pains start. Always before. Any thoughts on this??