I know it looks pretty bleak right now. Most of us have been there. But it's very unlikely that this pain-ridden state will be your life for now on. You are in the very early stages of finding the best treatment to control your disease. Right now you have been given prednisone, which is a standard first and temporary step to start to knock your disease down, and mesalamine, which is among the weakest and mildest of IBD drugs.
There are several other choices that might help get you into remission: immunosuppressants such as methotrexate and azathioprine, and perhaps more importantly, the big gun biologics: anti-TNFs Remicade, Humira, Cimzia, and Simponi, plus the anti-integrin Entyvio and the anti-IL12&23 Stelara.
Many of us end up on one of these biologics (in my case Stelara), since they are the currently the most effective treatments for Crohn's available. The point is there is every reason to be optimistic. You are just beginning your Crohn's journey. There are many therapeutic options that have not yet been tried. Plus, there is a lot you can do with modifying your diet to identify and avoid trigger foods.
The chances are very good that one or more of these drugs, perhaps combined with dietary changes and general healthy living, will produce a good remission that will enable you to live a more or less normal life for many years.