According to your description of the skin lesion (red bumps) and its localization (between the belly button and the pubic region) it doesn’t seem to me that you are experiencing some type of sexually transmitted disease (STD). The skin lesion you are experiencing is more likely a kind of skin infection that affects the hair follicles (superficial folliculitis). It can also be an allergic skin reaction. You can consult a dermatologist and request a balsam that contains a combination of antibiotic and corticosteroids that can be prescribed.