Agree with what is already being said. At this point, I don't think you have enough to go on to suggest gait changes. Get him in a good pair of shoes, get him running (or suggest he start with a walk/jog mix, more on that in a moment), and see how he progresses.
Really, I think his main issue may be his inconsistency, combined with the typical approach we see from younger individuals who are or used to be good athletes. He's probably trying to do too much when he does run and not running consistently enough. If possible (I know how hard it can be) work on backing off his intensity and building consistency. That, as much as anything, could go a long way in solving his issues. I'd even suggest backing up to where I normally tell beginners to start. That would be 20 minutes of alternating walking and jogging. Once he can do that without problems, then proceed. If he can't do that without problems after a bit of time, then it's time to enlist more help.
As for the toe/heel/toe form, that in itself can actually be a positive (see recent threads on barefoot/minimal running). While it does place some additional strain on the muscles and tendons of the foot and lower leg, it can be a beneficial form. Of course, I don't see the extent to which he's landing on his toe so it's very possible I have the wrong impression of his form but all I'd suggest is don't jump to conclusions about that just yet. Just because it isn't typical doesn't mean it's bad.
