Can psychiatric medication interfere with using cannabis?

Just so you know im a medical marijuana patient but anyways. I got into the mix of taking psychiatric drugs to deal with ocd which I realize is not working anymore. It just feels like it numbs my thoughts and emotions makes me a zombie. Cannnibus heals the mind makes things better makes me feel alive and deal with nauseau which was actually caused from the pills having a peptic ulcer develop in my stomach ,but I feel like it's interfering with the medicine I take ,kind of makes me feel spacey like out of it uncomfortable I believe in natural treatments. Now I'm wondering could there be a possible interaction? If I come off the medicine (zyprexa) will it make the herb more effective? Cause I'm done with all the placebo dangerous chemical meds.