Hi..
Thanks for the query..
Dry mouth or
Xerostomia can be due to causes like
Severe dehydration, Side effects of medications if you take any,
Salivary gland dysfunction.,
Nerve damage supplying salivary glands, Oral infections like thrush, Sjogren's Syndrome etc..
Swelling on face can be due to causes like
allergic reaction, tooth infection/ abscess etc..
So my suggestion is to consult an Oral Physician and get evaluated.
Treatment can be decided as per the diagnosis..
For dry mouth chew sugarfree chewing gums..
-Drink plenty of water.
-Avoid regular mouthwash and use specialized mouthwash that are formulated for dry mouth patients like Biotene..
-You can also instil artificial saliva drops..
-Suck tart candies as it also stimulates saliva flow..
Do cool compresses over the swelling..
Hope this helps..
Regards.