Actually the achiness only lasted for about an hour and then went away. I guess follistim starts working on your ovaries much sooner than clomid (which I was on for 5 months).
My RE said he was starting me out on a very low dose of Follistim because my ovaries looked like they might respond quickly to the medication--whatever that means!
Ya know I had the same thing the day after my first injection.. lower left, near my ovary. I am on 150IU of Menopur, which is 75IU FSH & 75 LH in each shot.. but mine have leveled out, and now at day 5 of injections, I am getting a little achey in my uterus and a little bloated. I know I will probably feel "fuller" as IO produce my follies.. but just letting ya know :)