Now could something be irritating him or is this normal? ANd help would be great
You say great and normal water parameters, but what about nitrate? As with all inverts, nitrate can be a problem if too high. Have you changed the lighting of the tank? What about water flow? Has that changed?
Where do you have your crocea placed in the tank? They are rock boring so they need to be placed on a rock. If left in the sand, it is possible that a bristle worm or other "critter" in the sand is irritating its byssal muscles. Move it to a rock if not already on one.
Another possibility is that he could be infected with pyramid snails. A nasty little pest to say the least. You need to look the clam over, especially on his underside if possible near his byssal to see if you see any of them or their eggs. The snails are extremely tiny. About the size of a rice grain. If found, manual removal is about the only course of action to rid them. They are some wrasse that eat them, however.
I am sorry I cant offer much help. I am fairly new to clams myself as I have only had my T. Maxima for about a month now. I have been trying to learn as much as I can in this short time but there is a lot to take in.