Large amounts of mucus in throat

Hello all,

I am 23 years old and was told I have GERD as of about 6 months ago. It all started when I went to see my doctor about mucus in my throat that I couldn't seem to get rid of. I was told it was GERD and was immediately put on Omeprazole once per day. A few weeks later after not much relief I had a scope performed on my throat and stomach and everything came back normal, no ulcers, hernia, or damage to my throat. Before starting the Omeprazole I never had any burning pain in my chest, but now it seems like its very frequent and it still hasn't done much of anything for the mucus in my throat. I am young, fairly active, never smoked, not overweight, and don't drink any caffeine so being diagnosed with GERD doesn't really make sense to me. Now if I try to stop taking Omeprazole I have extremely bad burning in my chest that Zantac cant even help. I also occasionally wipe blood when pooping. I told my doctor but she said it could just be something to do with my acid levels...

Is there anything else that could be causing these GERD-like symptoms that I'm missing?