If you had unprotected sex, you were exposed to so many different infections, not just herpes. It's true that herpes can be spread even if condoms are used, the same as syphilis. This second infection can also cause a rash all along the body in the secondary stage, but there are so many infections or reactions that can cause red rash along the body (not just STDs). If you had just unprotected oral sex, you were exposed to syphilis, gonorrhea and herpes. If you had anal/vaginal sex and it was unprotected, to those ones you would have to add chlamydia and HIV, The only way to know what's the origin of that reaction is visiting your doctor. You should also tests as follows :
-3 weeks after the encounter, for gonorrhea and chlamydia.
-6 weeks after the encounter, for syphilis,
-3 months after the encounter, for herpes.
Regarding HIV, you have two possibilities, if you go for a duo combo ag/ab test (4rd generation), the result will be accurate 28 days after the exposure. If you go for a normal antibodies test, it will be accurate 3 months after the exposure.
All the best.
Yes, you are at risk for those things from unprotected sex, and you should test.
However, none of those things would present with these symptoms. Herpes doesn't give you symptoms all over your body - no STD would.
Get yourself to a doctor to figure this out. It may be some kind of bug - bed bugs, maybe, I don't know - but it's not an STD. Definitely get it checked, and get tested for the rest.