That is nice about having well water. Do you have the well water tested for heavy metals, safety for drinking periodically. I am always concerned with well water which might have metals or possible other toxins leaching in. As long as the tests are god any you wouldn't have any concern about those dangers, then it could have been stress from previous care, lack of care and the moving and such causing problems.
Is the belly round or sunken in at all? Have you seen the poop? is it white, stringy clear?
Could be internal parasites if so.
But it would be helpful to keep the water as ideal as possible. To reduce possible added stress.