Normal blenny behaviour or a parasite?

[Sarah1990]

For the past 10 days or so I've been seeing my midas blenny nose dive occasionally into the sand and also occasionally bite just in front of its tail. I've studied all of the fish for ages and cannot see any white spots at all. I'm scared to do a freshwater dip because I dont know how to do it safely.
Is this possibly just normal behaviour or is it definitely a parasite?

 

[BeltedCoyote]

I do not know, so here is the gift of bump!

 

[Sarah1990]

I do not know, so here is the gift of bump!

Thank you, I've started polyp lab medic now just in case