This is a very atypical form of Herpes type 2.
I would also consider shingles, but I am assuming you have seen a doctor for this over the years and this has been ruled out.
Hopefully, the sores have been cultured and they have proven to be type 2 herpes.
Herpes infects nerves. It does not infect internal organs or joints but in patients who have difficulty fighting infection (cancer or AIDS) it can cause meningitis.
The outbreak could be causing your headache but it should not still be causing you to feel sick all over and it should not be causing joint pains at this time. You should see your family doctor or internist for evaluation--you may have another type of viral
infection, arthritis, bacterial infection.
You can look up dermatologists in your area on webmd.com under the find a doctor section or ask your regular doctor for a referral.
I hope this is helpful for you. I strongly encourage you to see your doctor because your symptoms just don't all seem to fit together with the rash.