Moving up to IV treatments. Looking for information and what this mean in relation to severity

I was diagnosed with arthritis (pretty sure psoratic) for 4 years ago. Now, Im 25 and my rhumatologist has decided we need to add Remicade to my cocktail. I have tried enbrel, humeria, and currently on methotrexate. My doctor wants to do a combination of remicade and methotrexate. I also have fibromalgia, going on 7 years now, so often I dont know what pain comes from what or what is triggering the other! Im on the 'best medicine combination' for the fibro that seems to be available. I know a lot about those medicines, but not much when it comes to IV arthritis meds. Should I be concerned since he said we need to be 'be more aggressive' about the treatment? At what point do they consider mild (I know Im past), moderate, or severe? Other than their 'medicine guide', what should I know and expect? Do it have similar size effects to methotrexate?