how to get all amazon category products
Maybe you should try to add two additional search parameters in your query - MinimumPrice and MaximumPrice - in combination with the keywords, of course. Then, whenever you get more than 10 pages for your search criteria, you should correct your min/mix price values.
That's how I was able to "avoid" that unreasonable limit that amazon set.
You're seeing a new limitation imposed by Amazon. From the Product Advertising API home page:
ItemPage parameter will be limited to a maximum of 10 pages for ItemSearch results