Started Gemcitabine infusion yesterday.

Hi 65/F stage 4 unresectable but contained pancreatic cancer. Started year ago went thru folinex ,had to stop that couple weeks short because it gave me colitis. Did radation. So couple weeks ago I was on chemo pills xelda if I spelled that right. Did 5 an half days ended yo in ER with horrible stomach pain that didn’t stop no matter what I took. So that was 2 weeks ago. So last resort doc wants me try low dose of Gemcitabine. Did it yesterday. By late evening horrible gas pains an gas. This morning horrible stomach pains again just like other chemo. This is only my first time taking this. He want 1x week for 3 weeks then 1 week off. I don’t think I can do it. Plus it gives me chest pain in middle of chest like before. Anyone else go thru this? Should I not do anymore. Thanks