Why am I still shedding on Oral minoxidil?

So, last June I started topical minoxidil due to slight recession of my hairline, I really didn’t have any other problem. My dermatologist told me he thought it was stress related. I used it for 6 months and I didn’t think it had did much for me, although looking back, my hair did feel a bit stronger. Since starting oral, 1 1/2 months in I started shedding and I still am, I’ve lost ground on my hairline and density. I’ve been on oral for 6 months today exactly and 4 months shedding, why is this?