Were you anxious before you ate the first time? I ask because, when our bodies begin to feel anxious our fight or flight response is triggered and the body starts to shut down unnecessary processes (such as digestion) that will not be needed if we start to run or stand and fight. This can very often make people feel sick and it can also block the hunger response. Once the anxiety has past the hunger response comes back and you can feel 'starved'.

Also, you mention an episode last week. With anxiety we tend to become anxious whenever we encounter a situation similar to when anxiety reared its ugly head before. So if you had anxiety when eating a sandwich before you may become anxious the next time you eat a sandwich. At first it may be only when you eat a tuna sandwich but in a short time it will become every sandwich. This is because we assume that the sandwich caused the anxiety and we will do EVERYTHING in our power to avoid feeling anxious again. Even if that means we never eat a sandwich again. When you notice this pattern it is important that you start working on reversing it with positive self talk. So if you think "I hope this sandwich doesn't cause me to be anxious" say instead "I am going to enjoy this sandwich and will be satisfied and relaxed after I have eaten it". Self talk is super important when trying to heal your anxiety.

I do hope you are feeling better.
Take care

I don't know if this is helpful, but many people are sensitive to gluten and it gives them a bloated heavy feeling. This is probably just anxiety, but it you want to try to test your sensitivity, you can eliminate gluten for a week or so and see if those symptoms go away.
Also digestive issues are common with anxiety, but my doctor put me on xantac for a month because even though anxiety caused the issues, they were real issues. The xantac helped after a week or so, but the issues can still come back when I am really stressed.

What I read into your post is that you have anxiety due to unknown physical ailments, not physical ailments due to anxiety.

What you describe could be a food allergy or intolerance. You mention eating a lot of sandwiches, therefore eating a lot of bread. Look up online at a reputable site, gluten intolerance.
If your symptoms are similar to what is described, then see a doctor to rule out other issues. I

have food allergies and know others with gluten intolerance and what you describe sounds similar.
Try a wrap on a corn tortilla. See if you feel better.

Hope you feel better soon. It is awful to not know what is wrong when we don't feel well.

In addition to all that's already been said, I have figured out over the years that some foods do not agree with me. Since I experience anxiety and depression, I am not always in touch with my body messages. But, for example, I figured out somewhere along the way that whenever I ate tuna fish I got a headache. Who knows why? Dairy products give me mucus; If I drink a glass of milk I can get bronchitis. This seems to run in my family. (Lactaid helps.) But the main point I wish to share is to perhaps pay close attention to what you eat and any body complaints that emerge afterward. Maybe tuna fish doesn't agree with you, either, for example.

Ravenous hunger is sometimes part of my panic attacks.

I hope you feel better, and get the answers you need.

Thanks for all the replies everyone! I honestly think it was just a case of anxiety and I was getting sick from eating the same thing over and over again, I don't have any gluten problems with bread because I've had toast this morning and nothing happened.