Sudocream (used for nappy rash) can be pretty good.
Consider changing your underwear (like cool cotton) and clothing down there to prevent the chafing eg if you're getting too hot down there then wear light loose fitting clothing to let the area breathe or if your clothing is rubbing.
If you have bare legs eg wearing a skirt, get some light cycle short type things or similar underwear to stop your getting hot and sweaty and rubbing.
Antibacterial bodywashes (eg Carex or Sanex) are good, don't use any perfumed toiletries down there, keep it simple and nice and clean and fresh.
If you wear pyjama's at night consider changing to something more flowing like a nightie (apologies if you're a bloke!) to keep the air circulating.
If it continues pop to your GP in case it could be some kind of fungal infection or similar which is irritating the area as there are some good creams and antibiotics which can clear it up pretty quickly.