How would you write mathematically that a random variable follows some unknown distribution? For example, if I had a random variable X and knew it followed a normal distribution, I might write:
$X \sim N(5, 10)$
What would I write if I'm trying to say that the distribution is unknown?
$X \in \Omega$
Is that correct? It doesn't feel right.

Standard notation is $X\sim F$ or $X\sim F(x).$.
Update: the latter notation, while common shorthand, could be misunderstood since $F(x)$ is a probability.
