'Alaskan Bush People' Matt Brown's Facebook Posts Cryptic Messages As Family Fears He's Dead

Matt Brown has some cryptic messages posted on his Facebook page amid concerns from family members who fear he might be dead.

On Wednesday -- the same day the "Alaskan Bush People" star was spotted near the same Washington river where an unidentified man later disappeared -- a lengthy post popped up on Matt's Facebook, which said ... "Feelings shift. Priorities change. Connections fade. That’s part of life, no matter how painful it is to accept."

The post encourages his followers to be genuine, appreciate each other and love deeply, but "never lose yourself trying to hold onto someone who has already let go."

It continues ... "At the end of the day, your relationship with yourself is the one that must survive every version of your life."

Several posts have gone up since Matt was spotted less than a mile from where a witness later reported seeing a man swept away in the Okanogan River ... but it is possible to schedule FB posts in advance, instead of posting in real time.

A couple of videos went up on his page yesterday -- tagged with #ThrowbackThursday hashtags -- followed by another ominous message.

Matt writes ... "Sometimes, the hardest task you must do everyday is to keep going. You know you can just lay there on your bed the whole day, but something inside you whispers hope to get up and urge you to fix yourself."

He continues ... "I know all this time, you've been trying hard to survive a day with deep sadness and you've been trying to find an escape from it. It is not easy darling, it will never be easy to pick yourself up again after a great downfall."

The post concludes ... "One thing that you should keep in mind is that whether you're okay or not, time won't just stop for you, you may be tired of trying to fix yourself over and over again, but trust your own strength darling. Tell yourself that you will never give up till the day you found your happiness."

Meanwhile, Matt's brother, Bear, says he's been told Matt had been seen near a river and was later observed floating in the water.