Hi..
Welcome to HEALTHCARE MAGIC.
I have gone through your query and can understand your concern..
As per your complain a black blister over the side of the tongue can be either an apthous ulcer or a
canker sore..
It can also be a hematoma caused due to
tongue bite..
It can be a
mucus cyst or a mucocele in case if it is present towards the side lying towards underside of tongue..
Dryness of mouth especially at night seems to be due to
mouth breathing habit..
I would suggest you to consult an Oral Physician and get evaluated and a thorough clinical evaluation can help in diagnosis and treatment can be planned accordingly..
As of now if there is pain in the blister you can apply numbing gel containing Choline Salicylate or Lignocaine.
Do warm saline gargles..
For
dry mouth if it is due to mouth breathing habit you can stick a vertical strip of micropore tape over the closed lips to enforce mouth breathing..
You can keep sipping water when you wake up at night..
You can also apply xylitol containing patches over the mucosa inside mouth as it will help in maintaining lubrication..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.