Yeah, you need to see a doctor. Don't understand C Diff either, but digestive problems are a common side effect of antidepressants and differ from person to person, so while you need to see a doctor it could very well be the Lexapro. Some people get loose stools, others get constipation. One reason for this is that they affect serotonin, most of which is in the digestive system, not the brain, and interferes with how the body naturally uses it. Another is they also interfere with magnesium absorption (and vice versa), also essential to proper digestion. If the doctor finds nothing wrong, assume it's the Lexapro. But one question -- you've been on it for 6 weeks -- did this start when you went on it, or later? And that's a really low dose, so if it is the Lexapro, this just isn't your drug.
I'm sorry but I don't understand what you mean about C Diff.
If you're having this side effect you need to contact your Dr. I know that antidepressants can come with many possible side effects. I've never heard of this one though from Lexapro. I've been on that medication myself for a long time and have never had this kind of side effect.
Please give your Dr a call. He.she might order blood work to see what's going on. I would tell them you want blood work if they don't recommend it. How long has this been going on?