Feed him on the other side and just pump for a day or two on the hurt side to keep your supply up and let it heal. Try to get a hold of a La Leche League leader or a Lactation Consultant, I'm guessing his latch isn't great if your nipple is dry and cracked.
Do you have a pharmacy that can compound on site? Usually this will be a "natural" pharmacy or a more locally-owned one. Call around and ask local places if they compound or not. If you fine one, have your OB write you a script for this:
"It seems to help for many causes of sore nipples, including poor latch, Candida (yeast), dermatologic conditions, infections of the nipple with bacteria and possibly other causes as well. It is always good, however, to try to assure the best latch possible, because improving the latch helps with any cause of pain."
The Recipe
* The antibiotic: Bactroban (mupirocin) 2% ointment (not cream): 15 grams. You'll need to get a prescription from your doctor for this ingredient.
* The anti-inflammatory: Betamethasone 0.1% ointment (not cream): 15 grams. You can get this over-the-counter.
* The anti-fungal: Miconazole powder, so that the final concentration is 2% miconazole. You can get this over-the-counter.
Sometimes it is helpful to add ibuprofen powder as well, so that the final concentration of ibuprofen is 2%. This combination gives a total volume of approximately 30 grams. Clotrimazole powder to a final concentration of 2% may be substituted if miconazole powder is unavailable, but both exist (the pharmacist may have to order it in). Using powder gives a better concentration of antifungal agent (miconazole or clotrimazole) and the concentrations of the mupirocin and betamethasone remain higher.
Get that latch worked out, it should never hurt or make your nipples dry and cracked when you nurse. Also, you can try these:
http://www.lansinoh.com/products/soothies-by-lansinoh-gel...
Good Luck! :)