Zollinger-Ellison

Hi I was daignosed with Zollinger-Ellison syndrome but I am going to be re doing the gastrin test because I had been on Nexuim for 5 days.  My level was just over 1000.  can taking nexium that short of time raise your gastrin levels that drastically?  My other question is I had one small ulcer then 6 months later I have 6 bigger ulcers, but show no ulcers in the duodenum. Tested me for H. pylori and celiac teice and came back negative both times.  What could be going on ?  Did the nexium give me a mis diagnosis or is it likely I have Zollinger Ellison