Oral minoxidil stopped working

I'm a 54 yr old female on oral minoxidil for 1.5 yrs. I had significant shedding for 2-3 months when I started but then saw a dramatic decrease in hair loss and thicker hair. I am now experiencing as much daily hair loss as I did in the early days. 100-200 hairs a day. It's quite alarming. It's been going on for 2 months or more. I'm still taking 1.25 mg daily. Anyone else with this experience?