Just remembered this thread so thought I would update. It was indeed sciatic nerve pain. A trip to the walk in Dr and a script for a muscle relaxer later and all its well.
The nausea has also mostly subsided thanks to a anti nausea pill.
I just had a pre natal appt today, 29 weeks and one day :) I'm still pretty nervous about the whole thing honestly but have a very supportive family and husband and have made my peace with it.
We're having a girl and plan on naming her Ella with Beatrice for her middle name for my grandmother.
Really can't wait to get back in the saddle :p I haven't been on my horse since November, my husband and parents are not horse people so it was easier to just give it up for awhile rather then the constant arguments lol. Not that my gelding minds the time off I'm sure, at least I'm pregnant in winter rather then prime riding weather, it's been brutal in NY this year anyhow so not sure how much riding would have been gotten in in any case.
Thanks for the support and advice everyone, I don't usually get so personal on forums but horse forum was an easy place to do so :)