Occupational Health Independent Medical Assesment

Hi all, after being off work 3 times this year due to relapses my HR department has requested that I attend an independent medical assesment. My employers have been supportive so far but I’m worried this next step is to implement some form of change that I might not want i.e. job change. Has anyone else been through this process? Will I have to do flexibility tests etc? Any advice will be appreciated.