worst pain ever. acid reflux. I took tums and one pepic. Any suggestions? can't sleep

Are you consistently taking the Nexium? I wasn't sure from your post. You could also try some of the non-medicinal approaches such as elevating your bed, or sleeping in a recliner. You may want to consider changing the time of day you take your Nexium. I found that taking my Omeprazole at night was best for me with a booster of Zantac in the morning on the days that that was needed. I'm glad you are taking the right steps and got a stress test, so many people assume it's reflux when they need to take cardiac into account. I hope it goes well at your endoscopy and they are able to get you on a regime that works!