Stocks declined Wednesday morning, nearing levels not seen since the Brexit woes of early July, and commodities expert Dennis Gartman, editor and publisher of The Gartman Letter, says they are headed for more trouble.

"A number of things have me nervous," said the CNBC contributor. He highlighted weak earnings, the Fed possibly tightening monetary policy and political circumstances both in the U.S. and abroad.

Furthermore, as the markets head into one of the worst months historically for stocks and with an election coming up, Gartman has a particularly bearish outlook on the markets and is buying protection in the form of the CBOE Volatility Index.

Gartman also noted that stocks have already had an "outside reversal week … where you've made a new all-time high and then taken out the previous week's lows, already in a mere two-days period of time, those sorts of things have in the past been very indicative of important tops."

Political confusion caused by the election means investors aren't seeing the U.S. as a place of safety anymore, Gartman said. Instead they are putting money into gold, which is why the commodity keeps going up.

"It's telling you that something unhappy is taking place," Gartman explained.

He added that he may get more bearish if by the weekend the market is still trading poorly despite stocks being in an outside reversal week and a good employment number.