Bipolar dad no longer taking meds, also refusing to honor child's gluten free diet

Ex husband has been seeing a psych for almost two yrs for bipolar. He has not been stable the whole time, and has decided he no longer wants to take meds. He had supervised visitation for the first four due to failed drug tests in court. He has now had traditional visitation for three years but does not utilize all of it- school days off are not his problem he says. He also is not honoring my daughters gluten free diet, since she was diagnosed with celiac disease six weeks ago. Sometimes he calls, sometimes he does not. Many times my kids do not want to go, but I make them. Now without meds and feeding my daughter the wrong foods, I'm very concerned. Do I have a leg to stand on? Do I need to go back to court with a lawyer? I'm in NYC