Acne after 5 months on Tret

I've been using tretinoin 0.1% for 5 months now and I saw great improvements (skin basically completely smooth). All of a sudden I've been waking up with whiteheads and bumps for the past two weeks and it seems to be getting worse I don't know what to do. There is also redness on some of the bumps. I don't know what to do. Nothing has changed in my routine, in what I eat, or anything. Any advice would be appreciated.

Routine:

Morning

I shower and in the shower, I use Cerave Hydrating Facial Cleanser

I wait about 15 min after I shower and then I apply Drunk Elephant's Vitamin C Firma Day Serum

If I go outside I Sunscreen SPF 50

Evening

I wash my face once again with the Cerave Hydrating Facial Cleanser

I wait about 20 min and then apply Tretinoin 0.1 %

This is the same routine I've been doing for months now and it would work great but I don't know why I am breaking out so much all of sudden.