Why is my pictus catfish right whisker curling up and shrinking?

it looks like a thin curled string now, as if a fish was chewing it up, the left fin is completely fine long and active, currently the pH is acid like 6.2 is that why? do pictus whiskers shrink when kept in acid pH? all of my tankmates dont seem to be bothering him, i just broke the tip of his left fin yesterday when i netted him, but is just a little piece by accident, he is still swimming but not as much as he did before, the substrate is nothing sharp just normal playsand, and there are no sharp ornaments