What causes little white blister looking cuts inside the lower lip it has sum pain when ii eat?

Aphthous ulcer: This is one possibility. These may come from trauma (brushing teeth to hard), stress or certain foods. They commonly have viral origins in which case they should last 3-14 days. Other possible causes include Crohn's disease, behcet's disease, vitamin/mineral deficiencies, immune deficiencies, and some meds. Any recurrent or non-healing ulcers deserve evaluation by a physician. Thanks to j. Batt.

Canker sore.: What you're describing sounds like a canker sore, also called an aphthous ulcer. It does not have one specific cause, but it can be brought on by many triggers such as stress, infection, vitamin deficiencies, or immune system abnormalities. Other than being painful, they are harmless and can be treated with topical oral agents.