Dry skin / red spots - Eczema?

Hi everybody.. last month I had a small patch of dry skin near my armpit, it was slightly red but it didn't itch so I didn't think anything of it and it went away within a week. Its been almost a month and the exact same pacth has come back in exactly the same area, except this time its surrounded by some small red spots - I tried the glass test and they don't fade under pressure. As well as this I have had exactly the same thing on my hip, dry white-ish skin with red spots, although all but one of the spots has faded in this area and the skin isn't red.. I'm trying not to worry but I have just noticed yet another patch of dry skin starting to form on my waist and I would really like to know what it is, it doesn't itch and I have no other symptons other than the spots.. oh and the fact both times these have appeared have been just before my period? Does anyone have any idea what this is? All I could find was eczema but I doubt I have that because it doesn't itch? Any help would be appreciated, thanks.