Started brushing my teeth 45-degree angle next to gum. bled a lot, it didn't hurt. next day, super small dots appeared on the bottom of the gum not hurt, next day mouth wall all the way at bottom, side has some white stuff that hurts, help, disease?

Probably not a disease. It appears your gingiva is inflamed. Early gingivitis. You really should be examined by a local dentist and have your teeth professionally cleaned.

You are probably brushing on gum which caused this bruise . You should hold soft tooth brush bristles at 45degree to teeth at inter proximal area and shim the body of tooth brush very gently without bending the bristles .This will clean the surface of teeth and the interproximal area . The white area is sloughing of gums which will disappear in few days , you may rinse with Luke warm salt water .