I would definitely not let this go but would get to the doctor. At the same time, ask for a referral to a dermatologist..I'd rule out staph first and then proceed to a dermatologist to see if this is a hormone-related skin condition or possibly an allergic reaction. You may need to ask for a referral to an allergist if the dermatologist determines it's an allergic skin reaction. Be assertive, take charge, and don't put off making these appointments because it can take time to get things lined up with different specialists.
Be sure to be detailed about when this has cropped up -- I agree with you that the tie to your pregnancies looks like a hormone thing but the fact it's back now is strange. I would not just go by what an ob/gyn said about a skin condition, if it has returned and you are not pregnant.