Feeling sick after eating, lost appetite, tenderness and pain in center of chest. Suggestions ?

Hello Dr Christensen, I have been feeling sick after eating and have lost my apetite. Yesterday I ate a handful of walnuts with a cup of tea and felt sick afterwards for quite awhile. Today I ate a potato in its skin with some grated parmesan cheese and a dob of margarine ( cholesterol free olive oil spread) mixed in. I felt sick afterwards for a couple of hours. I have been eating yogurt and that seems OK. I drink lots of tea and alternate between low fat and full cream milk. I drink a glass or two of wine in the evening. I am on Efexor FX 150mg and Thyroxin 75mg per day as ongoing stabilizers. I also have a tenderness and some pain in the centre of my chest ... about the sturnum area. Sometimes I can feel my heart beating more than normal. I recently had my full blood tests done and was fine. Do you have a comment for me? I am a bit puzzled and would appreciate some information. Thank you Dr. (Please do not use my email address for any other purpose than that of reply to this query. Please cancel my query if this is not the case. Thank you) Sorry I thought this service was FREE. I will have to cancel.