Dry scalp

Okay so I've started getting some bad dandruff for the past few months. I've tried head and shoulders, selsun blue (medicated), and this T Gel by neutragena. I don't wash my hair everyday day, maybe ever 4 or 5 days.

I still have dandruff after trying all those.

Anyways I've started going to the gym, I don't wash my hair everyday because I don't really sweat a lot but also because I currently can't afford a good shampoo and conditioner so I don't wanna dry out my hair.

I heard jojoba oil is good for my scalp so I massaged some on after washing my hear and left it on for day. Which I didn't know the longest I should leave it on is overnight THEN wash my hair. So anyways I massaged it on my scalp and left it on for a few days and we'll I go to the gym. Today is my wash day so I'm wondering if I'm doing it wrong?

I'm really confused on how to wash my hair now. Should I put jojoba oil on my scalp overnight and then just wash my hair tomorrow morning?

Would love some advice lol

Edit: so Ima shower cause I feel gross from the gym and nobody's answering lol but Ima wash my hair today and then tomorrow before I go to the gym in the morning Ima put jojoba oil on my scalp AND coconut oil on the rest of my hair (i usually do the coconut oil AFTER washing my hair and I leave it on for days but I looked it up and apparently that's not good either)... Then when I come back from the gym which I typically 2 hours, Ima wash my hair again and put some Garnier Fructis on my hair (not my scalp). Would that be good?