6-month old creatine monohydrate not dissolving well

I have some creatine monohydrate that I got back in April, and I'm almost out - there's probably 30 grams left in there. However, I noticed that it doesn't mix well anymore with my water; whenever I use it and shake it up in my blender bottle with plenty of water (20 ounces) there ends up being flakes and small bubbles that arise. And when I shake it, I do it a lot - even after a minute of shaking there's still small flakes

I know there's a difference because i just bought a new container of creatine (same brand, same type) and used 5 grams today - after 20 seconds of shaking it seemed to be all dissolved in the water.

Question is - should I keep using the last 30grams or just throw it away?