Your hp is low. Marrowgarr will hit for 15K-20K ever 1.2 sec. while the individual hit isnt much, it occurs fast enough that unless you can take a few of them, healing you in time can become a problem. (2 hits + an errant fire and you're dead if your healer just got spiked)
How to fix it? Rework nearly all your gems. So much wrong there that i dont know where to start. I would suggest ditching all the hit & expertise gems. Gem for stam unless the socket bonus is 9 stam or better (or 6 stam if you feel you're missing too many socket bonuses). Dodge/stam on red sockets, def/stam on yellow sockets. The PVP shoulder enchant on the shoulders.
Rework your enchants. Dont be cheap. Enchant for armor/health.