I guess the question now is, did it go away? It has been a month. I don't agree with petspectrum's diagnosis. This person seems to be suggesting something called benign paroxysmal positional vertigo (BPPV), which your symptoms do not match at all. Also, this condition does not involve tinnitus.
It sounds to me as if you have a temporary labyrinthine condition caused by adapting to the floating imbalance on the docks....There are tiny crystals which are in the fluid in the semicircular canals in the middle ear, and they can become dislodged and free, causing the fluid to not settle, (like a spirit level)...this can take 3 weeks to settle down, and it often causes tinnitus, (ear noises) as well......I have this a lot...