U could try using a cream/lotion with tea tree oil in to soothe the area & next time you shave use plenty of the lotion immediately afterwards. It also helps with regrowth as it can stop the hair follicles being irritated.
You can purchase products specifically for Shaving Rash. Try to shave in the direction of hair growth.
Also, it's important to exfoliate the skin regularly, to remove dead skin cells, which will build up over the hair follicle opening, so the hair is unable to grow out easily.
i have a lot of bother even on my legs if i shave and i've tried everything and nothing seems to work. i'm fine if i do it once every now and then but couldn've get away with it if that was my normal method of hair removal.
you can also get an epilator. some women swear by them but if you have a low pain threshold i'd avoid it. i do have one but not got round to using it yet
but like in the posts if you exfoliate with a mitt. try to avoid scrubs in that area if your getting a rash as it might encourace ingrown hairs