I have a similar issue. Oddly enough this started about 2 weeks after having some dental work done. I still have a cracked tooth but my dentist said that it is very small and if it doesn't bother me too much, to leave it for now.
I've had these little white bumps under my tongue, on the roof of my mouth towards the back and on the inside of my lower lip for about a year and a half. They do not hurt. They are uncomfortable as my mouth feels rough using my tongue. They just appeared one day. I have been going to many specialist in Vancouver over the past year and a half and have stumped them all so far. I've had WBC, RBC, Hemoglobin, Hematocrit,MCV, MCH, MCHC, RDW, Platelet count, Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils, Cholesterol, Triglyceride, HDL, Ratio T chol:HDL, LDL chol, Glucose fasting, ESR, Albumin, Alpha-1, Alpha-2, Beta, Gamma, Pattern, TSH, Glucose random,C Reactive protein, HIV serology and Rapid plasma regain blood tests. These tests were done over 3 visits and 3 months. All results were in the normal range. I've also had multiple swabs and scrapings of the little white bunps. Each time I'm told that whatever it is, it could not be grown but under the microscope, it appears to be yeast. I've been on Nystatin, Clotrimazole lozenges and Fluconazole to no avail.
Most recently I've had a biopsy done from under my tongue. The biopsy samples were sent for viewing under a uscope and for growing. As with the swabs and scrapings, they could not grow anything. I was shown the slides of the biopsy samples. The Dr. still thinks that the dots are yeast. It appears that during the cutting of the biopsy, some of the “yeast” was pushed into the lower tissue. Looking at the slides, he said that it does appear to be yeast but not a common strain. Normally the yeast has a couple of arms but the yeast I have has many and is similar to a bunch of grapes. My body does not see it as foreign and is not attacking it. The next step is for my Dr. to make an appointment with a microbiologist that specializes in yeast. My Dr. willl show the slides and hopefully they can identify the strain in order to determine the drug to eliminate it.
Swollen tongue: http://en.wikipedia.org/wiki/Glossitis
Dry mouth is called xerostomia and the causes: http://www.mayoclinic.com/health/dry-mouth/HA00034/DSECTION=3
Good luck!