New Golden Headed Goby Acting Crazy

[redcatcher27]

I'm relatively new to this hobby - I have a 14g biocube nano that has been in operation for a couple weeks. I transferred pretty much everything except some sand from my 5 gallon tank that I had going for over 2 years and it was doing quite well with no loss of livestock. Water quality is testing perfect. I know, some of you want to ring my neck already. But the 5 gallon tank did well. It just took us a while to out grow it. Now I love my biocube, but I just got a golden headed goby to go along with my blue damsel and clownfish. To clean the 2 - 3 inch live sand bed. He was doing well after bringing him home from the LFS for a couple hours, mining sand and all, until he decided he was somewhere else and then he dove under one of the live rocks. He's been there ever since. He's been trying to plant that rock on the bottom of the tank since then by excavating all the sand under the live rock. Until just a moment ago, when he went absolutely crazy, frantically swimming and darting all over the tank, banging himself into the sides, swimming fast, as if he had been bit by something. Or something. I have seen a bristle worm in the past, before the move... then he (or she?) was breathing heavily just being still against one of the sides for a few moments. Now he has returned to his cave.
Will he be ok? 'Anyone seen this behavior before? Thanks in advance for your input!