Weird hair

So I have pimples or at least I think that’s what they are on my scalp. They pop like pimples. I also have like some type of gunk/build up on my scalp. Has anyone ever had this? How do you get rid of it? I want to say this might be what’s causing my insane hair loss? Even after I get out of the shower and washing my hair it’s still like that....I use head and shoulders because I have dandruff and my hair is also super hella greasy so I wash it twice. Help me please!!!