It could be a regular infection, in which case the proper anti-biotics will help (some antibiotics are better for certain things; I don't know what would be best for this). However, I tend to get yeast infections in my c-section scar area, because the skin flops over it. This especially happens with moisture and heat (like in the summer). You can try some over-the-counter yeast medicine (just cream you rub on it); however, I do better with the prescription version of it.
Seeing a doctor would be best. If you can't do that, try to find a knowledgeable pharmacist, especially since you don't need a prescription for meds in Mexico. Unfortunately, if you take anti-biotics and it winds up being a yeast infection, the anti-biotics can make the yeast infection worse. So it's really best if you can get a real diagnosis.