Blister on lip for 10 months!

Hi,

I'm not sure if this is the correct place to post this, However my fiancee has a blister on his lip ( blister is about 2 cm long and skinny) which most likely was caused by sun damage, the blister is on his lower lip and is a yellowish/puss colour on top. It doesn't hurt him at all but it hasn't healed itself and it been about 10months now! - Does anyone know what this could be? I'm worried it could be cancer as it doesn't heal! - He has also had a liver trasplant about 6 years ago and i'm just wondering if this could effect his healing time in general?

Any help would be great?

[ronz8]

hi,
I get blisters on lips every month,  3-4 days before my periods.....is this correlated..? initially i thought it was an allergic reaction to a lip gloss....but last month i didn't use any lip product and i still got it....
its not painful...just tiny blisters that start on upper centre of lip and eventually move to the lower...subsides in 5-6 days...

Help...im worried