Here is a scale from the sticky's above you could use as a basic guide of some things to look for. Some of the pros here could probably be of more help than I.
Amoo's Severity Scoring System:
0 - Healthy Nem
1 - Tentacles shortened, still fully inflated, mouth tight, responsive to touch
2 - Tentacles shortened, still fully inflated, mouth slightly droopy, responsive to touch
3 - Tentacles shortened, still fully inflated, mouth slightly open, responsive to touch
4 - Tentacles shortened, still fully inflated, mouth open, responsive to touch
5 - Tentacles shortened, still fully inflated, mouth gaping open with insides exposed, responsive to touch
6 - Tentacles shortened, partially inflates, mouth gaping open with insides exposed, responsive to touch
7 - Tentacles shortened, inflates and deflates multiple times daily, mouth gaping open with insides exposed, responsive to touch
8 - Tentacles shortened, most always deflated, mouth gaping open with insides exposed, responsive to touch
9 - Tentacles shortened, always deflated, mouth gaping open with insides exposed, barely responsive to touch
10 - Tentacles shortened, always deflated, mouth gaping open with insides exposed, non-responsive to touch
11 - Mush (Sorry )