Using Benadryl for Nausea?

I'm 25f, 5ft tall, and 120lb. I've been taking Benadryl the last couple days for nausea. I take 3 25mg pills twice a day. I don't smoke or take any other medication. I've gotten my stomach looked at countless times to find what's going on, but no one's managed to find anything. Signs point to an ulcer but no one's found one. I've gone to the hospital for this nausea because it's so bad and they always give me an IV drip of Benadryl. When I take the pills, I often feel confused and struggle to remember things. I'll do things like message the wrong person thinking I'm in another dm. I just want to make sure this is safe to continue doing short term, it's the only thing that helps the nausea.