Ulcer?

Can anyone tell me what having an ulcer feels like. Today I’ve been experiencing some weird pain and nausea and I don’t know if it’s doctor worthy or if it’ll pass... so I’m nauseous, and have like a mild burning pain in my stomach and lower abdomen area (like intestines). I’m also freezing cold. And am unsure if I have a fever because I can barely get up without feeling like I’m going to pass out (feel light headed) or throw up