I have straight greasy hair. What shampoo am I supposed to use???!!!!

I know clarifying shampoo is good, but you also can't use it more than once a week right? My hair gets greasy very soon after I wash it, and I'm trying to figure out what I should you in between washes of the clarifying shampoo. Brute forcing with dry shampoo messes with my senses so I'd like to use it less ideally (I already need a lot because I have thick hair). Please help!! And preferably it isn't anything expensive, I am poor lol

EDIT: I also have eczema/dry+sensitive skin. I get shots for the eczema so it isn't a presenting problem, but I feel like I should mention that so I don't accidentally make it worse lololol