Los Angeles Rams starting Right Guard Jamon Brown has been suspended without pay for the first two games of the 2018 season for violating the leagues policy on substance abuse, according to NFL Network’s Ian Rapoport:

NATIONAL FOOTBALL LEAGUE
POLICY AND PROGRAM ON SUBSTANCES OF ABUSE

The illegal use of drugs and the abuse of prescription drugs, over-the-counter drugs, and alcohol
(hereinafter “Substances of Abuse”) is prohibited1 for Players2 in the NFL.

Moreover, the use of alcohol may be prohibited for individual Players in certain situations where clinically indicated in
accordance with the terms of this Policy.
[nflpaweb.blob.core.windows.net]

Makes some sense as to why he was only suspended 2 games instead of 4 like the usual PED suspensions.

If it wasn't prescription drug abuse and was the common social party drugs, maybe he was smoking some grass..

Either way it's bad news and he's in a contract year. Brown was probably the Rams 5th or maybe 4th best starting O-Lineman in 2017 depending on who you ask..