very worried about rash inner thigh, please help

Hello, would like some advice as I'm so worried about this....

about a week ago I was taking a shower and noticed a rash on my left inner thigh near groin area. Right away I came online and searched for answers... leading me to believe that I have Pityriasis Rosea or I  may have an STD!! It's not itchy, and theres no blisters or any pain, just red and dry and the skin seems to peel at the edges. I'm away from home now staying with parents for the Xmas period, so I cant just go and see my doc and get checked over as he's a 6 hour flight away! Today I noticed the rash is spreading a little underneath my bum area, and is getting redder. Some of it is small red spots and other is round patches. Cant stop worrying and checking online what its more likely to be. I went to a Chemist and got some Anti Fungal cream incase this is a fungal infection, applied the cream for the first time today, but the chances are it's not. I did notice the first week I got here, (about 4 weeks ago) that I had a circular mark, in the same place that the rash has now started.... which with looking online it seems like this was the 'herald patch'. which leads me to think I have either got pityreasis rosea or sphilis or even herpes. Some of the Pityreasis Rosea pics online look very similar to my rash. But what make's me worry its an STD is I did have unprotexted sex about two month ago :(, if theres one good thing that will come from this is a serious lesson learnt, never ever again! I'm just going to keep applying the Anti Fungal cream and hope the rash goes quick.. then get it checked out ASAP. I was going to stay here for 2 more months but chances are I'll leave within the month if this is still spreading and worrying. Need to put my mind at ease. Any help would be really appreciated, or if anyone else has been through the same, let me know how you got on. Thanks in advance.