The chemicals they use to make soaps "antimicrobial" are generally not supposed to be taken internally... You might also have knocked out some of your normal throat flora and that might have been part of the problem. The only time I use antimicrobial soap is when I have no choice and have to use soap since rinsing would not be enough. That basically means when I am in lab since the lab I currently work in is a pathogens lab (only a week or so left there and and onto one that does not handle human pathogens), I do refuse to use the secondary antimicrobial hand sanitiser stuff though! Tell your mom (or whomever buys the soap) about the article in this thread and about the dangers that anti-bacterial soap can potentially cause. I got my mom to switch (for the most part) over, she slips sometimes since I don't live there anymore but when I go home to visit I do an inspection and let her know when she buys something that is not on the Your-The-Mother-Of-A-Microbiologist-For-Goodness-Sake approval list (yes I have uttered that phrase on several occasions, there is also a father, sister, and grandparent version of it). Being 10 years older and having a 4-year degree and working on a grad degree in micro gives me a little more persuasive power than you Giardia, but if you explain your postition in a respectfull and informed way you might be surprised. Good luck!
~~Nonpathogenic microbes are our friends~~