Chaffing?

Ok so since being pregnant which is basically only 3 months I’ve been getting this chaffing like rash. It’s located right wear the underwear line sits. So it’s not from my thighs touching cuz it’s not rlly in tht area. It’s jst so annoying and my obgyn gave me an ointment the first time and it worked. But now I have it again. Is there any type of underwear or something tht would prevent it from even forming. Anyone have anything similar to this ?