So receiving oral sex puts you at risk for getting gonorrhea, chlamydia, syphilis, NGU and genital herpes type 1. Syphilis is uncommon in most developed countries, and if you already have oral hsv1, you can't get it again genitally.
Unprotected vaginal sex means you're at risk for all STDs. Obviously, her risk levels play a part, but if she has an STD, you're at risk for getting it. You not ejaculating lowers her risk slightly if you had one, but means nothing for your risk.
Scaly skin usually means either a fungal infection, or something like dermatitis, eczema, a allergic reaction perhaps, but if the partner you penetrated had a yeast infection, it's possible for you to get that. People can also have yeast in their mouths. It's also possible that you just coincidentally got a fungal infection apart from any of your activity - it's summer in most places, and there are heat waves everywhere. If you've been sweating, that can contribute.
Since you've had unprotected sex, you should get checked out. You can test for NGU, gonorrhea and chlamydia at 5 days, syphilis at 6 weeks, HIV at 28 days with a 4th gen DUO test, herpes at 12 weeks. I'd for sure get your skin checked out now, though.