edit: I don't know what exactly I did but I fixed it... I renamed my bones as for some reason all my bones had "L" on the end of them, I must have forgot to change the names after mirroring, maybe this will work for you if you have this problem too.
I'm trying to figure out why my character's upper leg rotates by 180 when constraining to my armature's bone. even if the weight is as small as 0.0001 the same thing happens. I've tried applying transforms and clearing but nothing seems to work, I'm really stumped. Sorry if this isn't enough information I'm not sure what else to write. Thanks.