Prices look different when viewed from different countries. This is because there may be VAT in some countries, etc. So if you're looking at different countries' Amazons, sometimes logged in to your account and sometimes not, you'll see differences.
If the price is different on your Bookshelf, however, you'd better contact Amazon directly.
I think different currencies also show different prices. The first thing to do is to check the prices on your KDP publishing dashboard/bookshelf. If your prices shows $4.99, this means Amazon has added the other $2.00 for whatever reason. I have the same problem, but I never consider it important to ask help from Amazon because I assumed this is for tax purposes or something. My books on the bookshelf read ($2.99), but on the product page, they read ($4.99). I hope this is the same issue. Ask Amazon Support for more clear answer.
I haven't really experienced the difference in price issues from one place to another. Then again, it probably wouldn't matter... for whatever reason, my sales have 'stopped cold' over the last two weeks.