Herpes can cause neuritis. If the clinician thinks there is possibility of HSV indicated in the plexopathy, it could be used. Antibiotics would be of much help.
"Herpes zoster or shingles is the reactivation of dormant varicella zoster virus (VZV) in the dorsal root ganglia. Segmental motor paresis is rare and only few cases of brachial plexitis have been reported in the literature. This case reports herpes zoster resulting in unilateral brachial plexitis with predominant radial nerve palsy. The patient was treated successfully with aciclovir, gabapentin and physiotherapy with good recovery. Radial neuritis secondary to active herpes zoster has been rarely reported in the past." Here is similar case report to answer your question.
Herpes zoster brachial plexopathy with predominant radial nerve palsy.
Jeevarethinam A1, Ihuoma A, Ahmad N.
Still I think, only your clinician can decide on it.
Dr Sharma, MD