Where was the shingles and is the sunburn sensation in the same place? If so, sounds like post herpetic neuralgia; there are several drugs to try such as the amitriptylline, antidepressant and the anti epilepsy tablets like gabapentin, and the creams like capsaicin.
Sometimes diabetic folk get a burning in a linear area from the back (painful radiculopathy) often if the glucose levels have just shot up.
It is generally said that most pains are worse if running high glucose levels, but I am not sure if this is true
There is a vaccination against shingles which is being rolled out and which seems very sensible
Best wishes