horrible diaper rash! 😭

Horrible rash that's been on LO behind since Saturday! I've tried destin and butt paste and bathing in Luke warm soap free baths and allowing diaper off. Nothing seems to work and pour baby screams when we have to change her diaper. Did notice she is having more then normal bowl movements that are more like a diarrhea consistency🤔
Her diet hasn't changed so I really don't know why this has happened! Could teething be causing it? I really don't know! 
Any other advice or should I call doc for a prescription rash cream?