Ending the PPS MDS?

I am a brand new medicare and medicare MDS nurse, I will be doing all the assessments (among) a thousand other things for the MED A residents. We have another nurse who does the MDS for the other residents. We are a brand new medicare certified facility, my question is we have a resident who had been here and already had their OBRA adm mds done, about 3 weeks ago but had gone to the hospital for about a week and now is back and he is going to go on MED A, I know I just need to do a 5 day for now, there is no sig change and I don't anticipate him being skilled for too long, right now it is for behavior observation and medication changes(was in med surg then to psych) so I figure once he is stable he won't have the need for skilled. When I make that determination does the Dr. have to say he is no longer skilled or do I? AND since he isn't getting any therapies do I just no longer do the PSS/MDS and just continue with his OBRA schedule that the other nurse will do? Thanks