I had not played him for a few months. Back then everything was fine. Now I came back from playing my other characters and thought I'd warm him up going through some easy early heroics before I moved into KOTFE. Only instead of warming up I'm dying in even low level heroics. It was NOT doing this last time I played him. What has changed? I have no hope of him getting further in game if your average 2 person heroic is killing him on the first mob. My guildies are not available to run with right now. And anyway I never needed them for these particular ones before.

He is level 70, Concentration spec. I usually solo stuff (due to guildies fading away) and stick to story.

how long ago did you play? The only post 6.0 change to sent i know of has been to buff combat spec slightly (not that I think it did enough to help that spec).

With 6.0, however, I do think they rebalanced heroics and companion healing a bit.