Hot Keys and Inventory items switching while mining

I'm not sure if this is 1.13 or 1.14 but the issue is: When I am mining sometimes what I am mining will switch places with the pickaxe. Like I have a diamond pickaxe in hot keys slot 2 and I am using it to mine redstone. As I move around mining the redstone suddenly I have redstone in my hand and am using it instead of my pickaxe. When I open my inventory the pickaxe is still there (not on hot keys tho). It happens no matter what my pickaxe is made of or what I am mining. The main thing that seems to affect it is how much I am moving around while mining. If I stay still it doesn't happen.  I am using the laptop's mousepad and keys. I do have the third button ("wheel") but it is not being used when this happens.