Very fast improvement indeed!
There’s a small stutter in your bow arm and I would suggest that it has to do with a combination of your wrist locking and your fingers gripping the bow too tightly, causing your small muscles to spasm or shudder slightly, creating that unwanted sound. I suggest relying more on the weight of your arm to produce consistent contact between your bow and the string. Relax your grip, relax your wrist (don’t drop your bow, though!) and allow the natural gravity do the work for you.
Keep it up!