How to stop my 6 month old puppy from chewing up the floor in the bathroom?

We have a wonderful, sweet and smart puppy that we rescued at 3 1/2 months and were told he was a boxer/Shepard mix (he seems like he may actually be a Great Dane or Mastiff/boxer mix though) and he is now 6 months old. We have had no problems at all with him chewing up until yesterday. We make sure to keep plenty of bones and toys around him and he always chews on those but yesterday we found him chewing up the linoleum flooring in the bathroom. His bone and two toys were nearby and he didn't seem to be doing it to be rebellious at all. All of his teeth came in last month so I don't know if he could still be teething but I don't want him to wreck the floor. Anyone know a good way to get him to stop this? We thought the bitter off stuff would work but I didn't want to get that if there was a better way to go about it. Any help would be appreciated! Thanks in advance!