Hard to say what is ticking it off...I assume no other corals were touching it?

It is pretty common for lobophytums (and other leather corals) to contract and look ticked off for several weeks IME. The contracting ends up making their colors look a bit brighter than normal...in your case more blue/green.

The best advice I can offer is to verify your water quality is good, possibly run some fresh carbon, and make sure it is getting ample flow. Typically after a few weeks in "ticked off mode", mine will shed their outer mucus layer and extend their polyps.

The dropping of limbs isn't all that normal for those corals. But I have had it happen and typically is the result of some sort of stress/problem.

The fact it is trying to extend polyps in the photo is encouraging.