Thanks for the query to H.C.M. Forum.
Cyst on the gallbladder
,it is not very clear at which part , this cyst is having, please mention.
As far as concerned about nausea
, gassy stomach, vomiting
May be due to hyper acidity, gastritis
Fatty food ( not digest due to cyst in gallbladder).
May be due to ulcer in stomach.
These symptoms didn't indicates towards cancer of stomach.
Consult a physician/ surgeon ( stomach problem & gallbladder) and get their opinion and help.
Hope I have answered your question.
If further any question I will help.