#11-15A fuse keeps blowing. why?

Well awhile back my #11 fuse blew, found out it was a Shiitty USB lighter socket charger. But now its blowing again, threw the charger away, I’ve read that sometimes an aftermarket HU can do it but I took the fuse out for that and it still blows, I noticed that a 30A fuse won’t blow, but then only my 2 center taillights works, 2 outside ones and I believe my 3rd brake light don’t come on, aswell as setting my alarm usually the lights flash, but no more. Brake lights work when pressing the brake though. And only blow when I go to put my headlights on, even after the first click for running/parking lights it blows. Any help is appreciated. And yes I’ve looked this up, that’s how I figured out the USB charger thing. And unless the HU is still in a circuit somewhere even with the fuse pulled. Thanks in advance.