What Causes Constant Sensation Of Nausea In A Person With PVC And Dyspepsia?

Question : My husband had an increase in his frequent PVC's recently and is very symptomatic with these. He has bad nausea with these episodes and has been evaluated at the ER last night and by his PCP today. He has had PVC's for some time and takes Atenalol 25 mg BID and PCP today increased it to 50 mg BID. His ER exam and tests results showed no heart attack. He was given Xanax 25 mg by ER MD and from his PCP to increase to 50 mg Atenalol twice a day. He took 50 mg Atenolol at 1pm and his first Xanax at 3:30pm. He is less stressed out but continues to have the PVCs and really the most disconcerting is his nausea. PCP ordered 2 D Echo doppler test for 2/27, Holter monitor 3/1/18, Treadmill and stress echo tests on 3/2/18 and a TSH test. He has similar tests before which have not found much. He does not have a history or blood pressure issues, or chol. He is 73 years old and avoids triggers that are usually attributed to PVC's. He has been riding his bike for the past 1 1/2 years every other day on average and usually goes 20 or more miles. He is really pretty healthy. Went down 4-5 pants sizes.

Several years ago he was diagnosed as having Dyspepsia Dysfunction. About 15% people have this and nausea esp. with eating is a symptom of this. He again had tests and found that his GB showed 20 to 30 % function by a hyta test. So he had this taken out. At the same time he was put on Elavil 50 mg to take one a night due to he was not sleeping post op weaning off narcotics after having a Total Knee replacement. His PCP ordered the Elavil to assist with sleeping. He was to participate in a GI study with a Specialist GI MD who treats dyspepsia dysfunction. But my husband called them and stated that his nausea symptoms were better since taking the Elavil. The office of this GI specialist stated that the study included giving the subjects either a placebo, an antidepressant or Elavil. They apparently did not need to see him since that time he felt better.

My question where is the NAUSEA coming from. Is it the PVC's or the Stomach dyspepsia dysfunction. He has no history of any other stomach issues or heart disease. I am going to get him some Peptol Bismol OTC but I am at loss.
I think if he sees the GI MD may be a good idea also. His PCP will call him with results of his tests along the way but does not need to see him for 6 weeks. Should he see a cardiologist he saw one who suggested the Atenolol and then did not need to see him as PCP would take over RX. He takes Prostate medication for his age and that is it. Please advise.
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Thank you very much will take your advice. I also gave him pepto bismol and tums as a back up. Ompersole we will also try if needed. His PCP also suggesting seeing GI spec. Will be setting this in motion.