The endoscopy should reveal quite a bit. Until you get the results, I would take the following precautions:
1. Avoid acidic or acid forming foods (coffee, soda, chocolate, tomato based foods like pizza and pasta with sauce, and most citrus fruits.
2. Reduce carbohydrate intake to a bare minimum.(sweets, grain products, starches)
2. Eat small meals only.
3. Chew your food more thoroughly before you swallow.
4. Don't eat or drink within 3 hours of going to bed (or lying down for any other reason)
All of what you describe can be caused by heartburn/indigestion/acid reflux, even the spots of blood. Sometimes when the acid get up that high, small amounts of it can get into your lungs on the way back down, which might cause you to cough up mucous with a little blood in it.
The omeprazole can take a full week or more to become fully effective, and your dose may need to be increased, but I would not tempt fate with pizza even while on it. And you should not be on it any longer than necessary. Doctors routinely prescribe it for long term use, but you should learn about the possible consequences of doing so. If it turns out you are going to be on it for more than a few week, I highly recommend you supplement your diet with calcium citrate, magnesium, Vitamin D3 and B12.
And of course, you should look into the cause of your anxiety, as that seems to be the starting point for all this.