Tomorrow begins my 2 day appt at Shady Grove. I received my instructions. I am having an HSG early Wed morn. I had one back in 2007 at Penn, which was no big deal. Any idea why I need to take 2x500mg of antibiotics the night before? I am kinda worried about this. 200mg usually makes my stomach a bit upset even with food. And now 1000mg? I've voiced concerns to the staff but as long as I wasn't allergic they wanted me to go ahead. Seems more reasonable if I could take one tomorrow morning and one tomorrow night? Any thoughts?