How can I get rid of a rash I have from shaving under my arms, and on my inner thighs and pelvic area?

Rash & Shaving. Rashes have to be seen. One possibility is irritation from the shaving blades or from the cream, lotion or foam used in those areas , try antihistamines by mouth or topical Benadryl (diphenhydramine) or caladryl. Try or test it in a small area some cortisone cream like Hydrocortisone 1% ( avoid it if there is a question of pus or infection). If rash is too much or has blisters or pustules or many wheals see a dr.