None of this would be caused by herpes. 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.