Fmla violation?

Hello. I have an ADA confirmed disability that I have asked my employer for the last 2 years to accommodate, until recently they would not. Since my employer never gave me the option of an accommodation, I have Ulcerative Colitis & was asking for an extra bathroom break, I ended up using FMLA time so I would not be diciplined for extra bathroom breaks. At my company when we take FMLA we must take it concurrent with available pto (vacation & sick leave) So because I was essentially made to take FMLA (Mimimum of 2 hour increments) to accommodate my necessary bathroom breaks I have exhausted all of my PTO at this time. Last week I was I'll u related to my FMLA, went to the Dr & brought in a note and am now receiving diciplinary action up to termination for missing work, which aside from my FMLA I have missed 2 days in the past 12 months so no excessive absences. Is this legal? How can the company basically dicipline me for missing work after using all my PTO when their policies are the reason I used all of my PTO in the first place?