L.R.
Some foodborne illnesses last more than a day or two -- they can last for one to two weeks in some cases with symptoms decreasing but continuing even as they lessen. But you have no idea if that's the issue here.
Please see a doctor immediately. No matter what this turns out to be -- a simple virus, a foodborne illness, gall bladder (which can cause these same symptoms), kidney stone (yes, can have similar symptoms too) or a "hormonal sickness" (not sure what you mean by that -- "period-type" cramping doesn't mean a lot, only that you're cramping....) -- whatever it is, better to KNOW than to ask us for diagnoses online. Why the reluctance to see a doctor? If you have something like salmonella or E. coli, that can be passed to other family members as secondary infection if you have it -- you need to know if you do or don't. And if it's a stomach virus, same thing; others are at risk (especially your infant). Finding out if it's foodborne or a virus only requires a simple blood test.
Get to a doctor. You may be dehydrated after the vomiting, or your electrolytes may be thrown off, or you may be pregnant depending on exactly when you re-started your BC method after the birth (for real--Google it if you don't believe me).