Well, bad news. Cerebus died.
However, I know the culprit. It wasn't lockjaw. My testing strips have been giving me a bad reading apparently. I took some water into my work to study it with our colossal amounts of test kits and turns out my nitrites were sky high at 10! I threw out the old kit which wasn't expired so...I don't know what the deal was. I did a 35% water change and used Amquel Plus and slowly it has come down to normal. Unfortunately it took the loss of a fish in the process.
I really began to worry when my second puffer (my oldest, Barlow) stopped eating, as well. However, he is eating and active and chasing brine shrimp and snails and everything. He is such a trooper. I have seen him out live two other puffers so I am thinking I will just keep him by himself for now on since my luck with second puffers isn't really too great.
I clean my tank regularly. I move rocks, plants, everything. I just don't understand how my nitrites got so flippin high.
Would I have a more accurate reading if I used the liquid test kits? I had 5-in-1 strips, but I really wouldn't mind the extra individual testing.