Air carrier First Officer reported a loss of control while encountering severe turbulence.

Narrative

We were at cruise at FL350 ATC had given us direct ZZZ and handed us off to Houston Center. The radar was clear ahead of us. We checked on with Houston and they gave us a reroute. While copying the reroute it began to get bumpy very quick. The Captain reached up and spun the heading bug 90 degrees right. The autopilot kicked off almost instantly and before I could grab the controls the Captain said I have the aircraft. I saw we were in a 25 to 30 degree bank so I reached up and put the heading selector in the 15 degree setting. The turbulence/sheer was bad enough that we could not hold airspeed and altitude. At that point the shaker went off for about a second or two and the Captain followed the upset procedure. We informed ATC that we needed FL330 and of the severe turbulence. They gave us descend to FL330 and we did. After the level off at FL330 the autopilot was reconnected. We informed Dispatch. After arriving at the gate; we sent a an ELB (Electronic Logbook) report and informed Maintenance.