Turn signal blinking fast

I have aftermarket turn signals that were on the
car when i bought them. The look like led arrows.
The right turn signal has been blinking fast and
says check rear turn signal light but none of the
lights are out. The manual doesn't specifically say
what fuse is for the turn signal but i saw online it
was called BCM and replaced it just to rule out the
fuse. Im assuming i have to check my turn signal
relay next but i can not find it. Where would it be?
What else could be causing this?