Groin rash 4+

[Rashes122]

Hi I have had this rash in my inner thighs and we're m my underwear meets my skin. It is been there for four months plus and I've been to six doctors and they still don't know what it is.  It is sore and it kind of pinches near my underwear I wear 100% cotton underwear. And I know it is not a sexually-transmitted disease because I'm not sexually active. It gets quite read and angry and I can't go to the gym very often because it hurt so much I also can't do long periods of standing on my feet at work because it hurtS so much First I was diagnosed with female jock itch and I was given a whole load of creams . my one doctor Who is a female asked me if any doctors had ran a blood test for Donna swab no I said so she did blood test and a swab and nothing came back. Then I was told it was a yeast infection was given  meds for that. Nothing came of it still have the rash then I was told it was a fungal infection was given cream for that. Still have the rash. Then I went and saw a Doctor Who specializes in some sort of dermatology but isn't a dermatologist . She diagnosed me with erythrasama and put me on erythromycin for it is now two weeks later and I still have this rash. Some of it is cleared up but most of it is still there and today it just got angry again. Or use 100% unscented natural products on my body nothing with a lot of harsh chemicals in it. All of my soap is unscented. I am at a loss for what this is it's not fungal it's not yeast  and I'm not sure if it's bacterial. Can anyone help ? I am using dapper rash cream just to stop the rash from getting mad but this seems like an endless circle . It is ruling my life and I don't want it to . The last doctor told me I should just suffer through the pain and lose weight . I'm not that much over weight about 5'8 and 209 pounds . I use to be 222 pounds . I carry most of my weight from my thighs to my chest . My body has more muscle than fat . I had an  assessment done not even six months ago on my body to fat ratio. Thanks if anyone can help.