Find all integer solutions to an equation

Whenever I'm confronted with a question bearing the label of 'find all solutions' I almost never know how to solve it algebraically (apologies if I spelt that incorrectly), I always have to resort to manual methods, which usually are a bore and I know that is not the true mathematical way to solve them.

Now I've been shown this equation:

x^2+y^2+x+y=1001

and I have to find all integer solutions.

I have no idea of how to solve this because I think the left half of the equation cannot be simplified (or I simply do not know of the method). Until necessary, I'll refrain from using the calculator so please could anyone help me?

~Cyfer