Probably intertrigo. A doctor can prescribe an anti-fungal cream to treat it.
@Cory what brand do you recommend?
@Sophie what brand do you recommend?
You can also uses tea tree oil if you prefer a natural option
I get rashes too from moisture I use bacteria cream
I get the same under my arms. I usually use an anti fungal cream to treat it. And for prevention I use tea tree oil a couple times a week
Looks like intertrigo. Your derm can rx you Ketoconazole cream for the fungal portion and Mupirocin ointment( antibiotic) since you have lacerations in your skin….or they might can give you a combo of nystatin-triamcinolone cream. They will let you know what’s best for you. 
Yeast… try an anti-fungal cream…