Same thing here, but my severe neck pain & stiffness started as the cold sores were starting to fade from topical salicylic acid and acyclovir.
I also had two of them, symmetrically on my lower lip. By the way, are yours blisters or more like nodules with occasionally a little whitehead with nothing in it? Mine are the latter.
You have Crohn's Disease, right? I've been diagnosed with IBS from time to time. I'm wondering if either the particular strain of cold sore-causing virus is different than what others have, or maybe isn't even herpes simplex at all but something not yet IDed. The lack of classic blistering sores tells me it's different.
The symmetrical thing makes me think the virus as it is traveling back along the spin back to the base of the spine might be jumping nerve junctures and coming back up through a mirror-side nerve ending. Your body is layed out like that and a lot of these viruses hibernate in the base of the spine. It would explain the pairs of symmetrical ones. In my case, I get one, then I zap it with some stuff and as that one's going away another one pops up on the mirror spot.
Can't be a coincidence. The neck pain could be the result of local viral infection as the woken-up virus travels back up the spin or back down. The neck's nerves I think have more groups of junctures, so they might be trying to move around to somewhere else as your immune system attempts to stop it.
I strongly suspect whatever this virus is, is a cause for IBS/Crohns and weird pseudo-acne breakouts. Acne, after all, requires initial inflammation to create an environment in the pores that invites abnormal strains of p. acnes and staph bacteria into the pores, where usually only good strains of p. acnes live. It might be triggering certain types of acne, too, by initiating lumps or inflammation.
are you sure these are cold sores? having one in each nostril is a bit unusual.
you need to be seen if you can barely move your neck. discomfort in your neck wouldn't be too unusual but it wouldn't be enough that it would hurt to move it/restrict your movement this much.
not unusual at all to get cold sore recurrences when otherwise ill.
grace