Hall effect module jitter.

This is hard to answer without knowing:

  • What you mean by '10 digits or more' - that the raw reading on the analog pin varies by +/- 5, or something else?

  • What device is drawing the current, and what is the power supply to that device?

Unless the power supply to the load whose current you are measuring is smoothed and regulated DC and the load is constant, you can expect fluctuations.