What causes you gums to be sore/sensitive?

Gum: Gingivitis, poor dental hygiene, immunosupression , chemotherapy, diabetes, a cold, apthous sore, dilantin, trauma, dentures etc.

Infection: When your body cannot contain a bacterial invasion of body tissue, an infection occur. An infection gives rised to tissue vasodilation and neovascular genesis (produce new blood vessel and capillary) to mobilized the cell of immunity to combat infection. When this occur, gum tissue is gorged with all these cells and pressing on the nerve causing sore or sensitive.