I have a rash, it seems to target the parts of my body where i sweat most? could it be an allergic reaction?

Maybe : It may be due to a local allergic reaction to something touching the skin (what we call a contact dermatitis), such as elastic material in the waistband of underwear or bra. More likely it’s a heat rash. Try avoiding tight clothing, drying skinfolds with a hair drier on cool setting after showering. If the rash is located in skin folds or under breasts, it may be due to a skin yeast infection.