Can an allergic reaction from steri strips on your C-section site spread up your stomach and on ur feet?

Yes and no. Allergic contact dermatitis is a likely explanation for the reaction on your abdomen with the allergen being moved from the operative site through handling or incomplete cleansing of the affected area. It is much less likely that the foot involvement is related, and could be the result of another process.
Not usually. While it is not impossible for some componant of the steri-strip to cause a wide spread reaction, it is more likely to cause a localized irritant type reaction at the site of placement. I would advise you to see your doctor for evaluation of the rash to make sure something else is not going on.