3rd month on Accutane 20 mg; want to discontinue. Can I?

What you describe is normal. You should discuss your concerns with your doctor. Flares are normal in the beginning. Depending on your weight, acne, and tolerance, you will most likely need a higher dose eventually. 

Most of my patients become read and their lesions become inflamed with Accutane.  It's part of the process and does not lead to scarring.   I have had some patients who do not see major results until the fifth or sixth month of treatment.   Discuss with your doctor and don't stop treatment because of some redness.Wait until the miracle of Accutane happens and you'll be glad you did.

Accutane forces everything under the skin to come up and out so it can change the oil glands and pores. That means all of that was under the skin and going to come up. As long as you know that your acne is NOT resolved, and you will continue to have breakouts and issues, then you can discuss stopping with your dermatologist. But Retin-A is not a long-term cure. It only treats the acne that is present. It has no ability to stop future breakouts. So that means you're on it continually. "This
answer has been solicited without seeing this patient and cannot be
held as true medical advice, but only opinion. Seek in-person treatment
with a trained medical professional for appropriate care."