None of this would be caused by herpes
wouldn't give you spots on your arms, cause arm pain
, or weight loss (if only). While herpes can give you leg pains, it wouldn't coincide with arm pains, dizziness, worsening muscle pain with exertion, etc.
Clearly you have something going on, and it doesn't sound STD-related. I'd ask for an MRI of your back, and if that's ok, see a neurologist.
Even if you for sure got herpes (which I don't think you did), I'd still suggest this.