Remember that this won't last forever, although today it sure seems like it might (throwing in my personal experience here)! I do know it's hard to have a little one depend almost completely on you for everything.
Others have had some great ideas for distractions. If you try a gentle distraction and he doesn't want to take it, he'll let you know that he really does need to nurse. Offering to play a favorite game, offering a sip of water instead, pulling out a book ... all are ways to distract him temporarily. For more ideas you might want to check out Mothering Your Nuring Toddler. Good luck!