Welcome to Health Care Magic
You are intelligent indeed!
You have listed all the possibilities! The last one is the most likely possibility - the tablet has gone, but the irritation caused by it continues to give such a feeling.
I have several such instances / even had to remove a few by endoscopy
- most of them were with capsules, some from food!
You need not do anything. Just relax and watch out. Antacids may help. If you are still disturbed after a day or two, an endoscopy will help - there may not be the tablet / but the remaining mucosal injury
will be the tell tale evidence / You will be reassured...
Wishing speedy recovery