Will medicare check on pre-medicare medical history for a possible upper endoscopy.

Medicare should not deny a medically necessary endoscopy just because the earlier procedure was before Medicare or three years ago. The current clinician documents your symptoms and medical necessity; coverage and cost depend on diagnostic versus screening status and whether you have Original Medicare or Medicare Advantage, including any prior-authorization rule. Ask the gastroenterologist to confirm the diagnosis code and authorization requirement before scheduling. Education only; I am not a licensed agent or affiliated with or endorsed by the U.S. government.

Medicare should not deny a medically necessary endoscopy simply because the earlier one was before Medicare or because it was three years ago. The current clinician documents your symptoms and medical necessity, and the provider submits the claim; Medicare generally does not need your old pre-Medicare claim history to decide eligibility. Coverage and cost depend on whether the procedure is diagnostic or screening and on your coverage (Original Medicare vs. Medicare Advantage), including any plan-specific prior-authorization rules. Before scheduling, ask the gastroenterologist to confirm the diagnosis code and whether authorization is needed. Education only—I’m not a licensed agent or affiliated with or endorsed by the U.S. government.

@db58528269 

Both test would be covered if medically necessary

The Colonoscopy would  be covered either as preventive or diagnostic depending why you are having it at this interval - Preventive is covered as NO out of pocket cost to you but diagnostic would be at the regular Part B rate so that is gonna depend on your risk factor (see the link). 

.Medicare.gov - Colonoscopies (Screening)  

The endoscopy can be used for either diagnostic or sometimes theraputic reasons and it would be covered under the regular Part B payment schedule.  You pay your part (or have it paid for you if you have a Medigap policy) and Medicare pays their part. 

CMS.gov National Coverage Determination - Endoscopy