I suffer with this, it came out of the blue a few years ago and it's horrible. My GP couldn't really give me a cause or cure other than suggesting a dentist check up to rule out a problem. When I get it now it's never been as bad as the first time which lasted for weeks and made eating difficult. Nothing really helped much, try sucking ice chips, sorry I'm not a lot of help I have sympathy.
Is wealth inequality causing the big issues of our day?
