Hello and welcome to the forum. Thank you for your question. We're sorry you are having this difficulty. We understand about not going to your doctor's office under the current situation and that is wise. However, I do want to point out that most doctors are currently being more lenient with what they will do via phone or video chat on computer. They are practicing what is called 'telemedicine'. So, they will give advice without your physically leaving your home. It is like a doctors visit but virtual. So, if it becomes too concerning for you to wait to be seen, that is always an option.
In the mean time, a couple of thoughts. I do think you are likely correct that the new sit up routine has impacted your abdomen. The sitting position may put those muscles in a way that then results in the discomfort. However, I do want to point out that patients often report having more abdominal pain in the sitting position when they have a peptic ulcer particularly when lower in the abdomen such as in the pylorus or leading into the duodenum.
Things I'd try, stop smoking if you smoke, limit or eliminate alcohol, watch for foods that may trigger the symptom and alter your diet, eat less spicy food, limit caffeine and discontinue use of Nsaids.
Would you describe your stool as more loose than normal or harder than normal in consistency? And has your diet changed at all as I know my family has had to make several alterations to our typical patterns.
That this is not severe pain, all day and accompanied by nausea or vomiting are good signs.
Hello~Have you been checked for a hiatal hernia, this could possibly be contributing to your problem, When we sit, the hernia is pushed up through the diaphragm and this can cause the pain you are having, very possibly, those exercises could have started this and now, it is pushed through the diaphragm causing the issues. I would certainly ask you doctor about this.
In the meantime, try drinking some very warm water, as you swallowing, give a good bounce, this might help to bring the hiatal hernia back to where it belongs.