Couldn't say which species it is, but it definitely looks like it's sick. Those are some odd looking marks on it's tail and back as well. Doesn't seem to be the typical boat prop scars? Hopefully, it pops back up somewhere and the NWA can get to it...
There's also some good info on the IUCN site - http://www.iucnredlist.org/details/22103/0
It's been a few days now and I've only heard word of one other person spotting the Manatee. Still holding out hope though! Been in the water even more often since this hoping I'll get lucky again.