I think there is a difference between prodromal and early labour. Prodromal is what the rest of the ladies seem to be talking about, start and stop labour that comes and goes depending on what you are doing. Early labour is supposed to be the labour from 0-3? cm and for some women can take a long time. It can be exhausting and frustrating and is usually due to baby being in a not-optimal position. Try some of the exercises on
www.spinningbabies.com and see if that helps. Also, get rest if you can. I know that I went through "early labour" for many days with my DD and it was exhausting. If you need to take something to help you sleep then Benadryl, Gravol and Unisom are good options (Unisom is the best, but not available to everyone depending on thier location).
Good luck, I hope things speed up for you or stop to give you a rest!