The ups and downs are natural, learn to pat yourself on the back when you solve a problem, when you progress.
Be also open to notice your inner calling. What does it say? Is there something else in your life right now that needs more attention than making art? Can it be that you want to explore a new area in art, maybe you are now interested in different themes than before? Notice what you really want. Something might have changed and you might have a different call in art than before.