I have what started out as a pimple and seems to be infected. it's right where my legs rub and it is swollen and warm to the touch.

See a DR: You may benefit from a drainage of an abscess. Do not use Benadryl (diphenhydramine) except as a sleeping pill.

Be careful: Do not touch or squeeze it and use warm compresses 3-4 times daily so it may drain on its own. If it gets larger, painful, or the redness spreads, or of fever you will need to see a doctor to get antibiotics and possible drainage.

Infection = Doctor: If it's infected, the best idea is to see your provider. It may be quite easy to clear up - but it's not a D.I.Y. project - you'll probably need a Rx. Do it soon so it doesn't become more complicated by spreading. Hope it goes well. Clean, cool (ice pack) compresses may reduce discomfort till you get treated.