Tail lights acting erratically, pressing on brakes causes different lights to act differently.

So then, my tail lights are acting up, whenever I have my lights on for the
dark my tail lights will dim to a very low extent, if I turn on my turn signal
then everything will flash. Including the lights that shine on my license plate.
When the lights are turned off and I use a turn signal then brake, then the
turn signal will dim and the brake lights are very dim as well. Used to have
a trailer hitch, since removed due to a prior lights issue. Checked up on the
ground, didn't seem to look too corrode, however I did not remove it to
look. I have followed the wiring under the car to look for breaks in the wire
somewhere to no avail. I have yet to check the fuses. Any advice is
appreciated.