You note that you will need visas. I imagine you have heard this from others already, but do be aware that you should not underestimate the difficulty in getting a work visa. Unemployment (and underemployment) are still very much a concern in Spain.

You didn't mention it, but should we presume that you and/or your mother are fluent in Spanish? In particular, I mean able to use the language for work. Your language ability will open (or close) doors in many workplaces.

If you are not already fluent or nearly so, then you should start studying, and perhaps even consider an immersion course (e.g., Guatemala has very good and very cheap language instruction -- though the dialect will be a bit different from the Castillian spoken in Madrid).

Suerte,
Michael