I think you are stuck with this Tilly.
we were using this as a lab agent in the seventies
see
http://lib.bioinfo.pl/auid:293133
The nature of latency means that the same area should be affected by recurrent cold sores - the big thing in the seventies was that if you transplanted the skin somewhere else would the rash follow?
And it didnt - it reappeated in the original site (showing latency in nerves)
and yours seem to be spreading.
Think Herpangina.
I think it may be worth a trip to your GP to discuss whether oral acyclovir is necessary. I have to say I took it myself when I was immunosuppressed and it seemed OK.
and yes I think they may be cold sore blisters in your mouth (but they are meant to be painful)