I am currently 103 pounds and doctor suspects crohns, what can i do to keep from losing more weight because i can't afford to keep losing weight?

Depends why: I assume your doctor is in the process of investigating why you are losing weight and is suspicious of chron`s disease? If CD is the cause then it is best to treat your disease, weight gain will then follow. For now speak to your doctor any methods you can use to slow down episodes of diarrhea.

Get medication: If you truly have Crohn's it will be extremely hard to gain weight until your Crohn's is under control. So the best thing you can do is get the tests done that they want and then start therapy. Often GI doctors will put you on supplemental shakes to help "stave off" the weight loss. In truth, it'll still be hard to gain weight until your disease is managed.