FMLA question

Nicole

So I’m 11 weeks tomorrow I have had a miscarriage and I was in a car accident in which my pelvis was broken in 4 places....my dr has me on a 25 lb weight restriction I am a RN and work as an MDS Coordinator I have to be on call every 3 weeks for 7 days straight...I sometimes have to go work as a nurse or a nurse aide if I can’t find coverage....they have had my FMLA paperwork stating my weight restriction since last Thursday and worked this weekend (because I was on call) and yesterday and now they are telling me I have to take my 12 weeks leave now or get the weight restriction taken off which my physician will not do....my job description does state I must be able to lift at least 50 lbs but doesn’t say if I cannot do this I can’t work....can they legally do this???