I have a lump on the roof of my mouth that sometimes swells up and gets sore and keeps causing me to get a sore throat and infection. my dentist have said its dry mouth but i'm not convinced. i'm currently using toothpast and mouthwash for this?

Such a lump is not a likely cause of sore throat or other infection. If you haven't seen a dentist when the lump has swollen up, do that next. If your dentist has examined you at that time and says nothing is wrong, you can rely on that as well. If in doubt, get a second opinion from an otolaryngologist (ENT specialist) -- also preferably at a time when increased swelling is apparent. Good luck.

If the t'paste & mouthwash are not helping, repetitive unhelpful results say, "search for another answer." Seek evaluation by an OralMedicine specialist. Your local Dental Society should be able to provide you with list of Oral Medicine specialists in your area. Or seek evaluation in the Oral Medicine Department of a University Dental School.