Dewormer question - Gastritis

I have had gastritis for 7 months now and it just won't heal - everytime I try to wean off my medication (Nexium) the gastritis comes right back. I've been through MRI's, Cat Scans, Endoscopies, Ultrasounds etc etc - all negative. I have passed stringy wormy looking things in my stool over the past months and I'm now thinking that I may have parasites/worms ???? My question is, Is the Dewormer gentle enough on the stomach to use if I have gastritis - I just don't want to make my condition worse....... Thanks Tweet