Welcome to TE, KateNTx!

You mentioned that you had been riding only a few days, after many years of not being on a bike. Whenever one starts riding (e.g., after a winter of not being in the bike), your sit bones feel a little bruised. I would definitely change the saddle (TE also carries some nice ones) and look at the over all fit of your bike. If you are able to touch the ground with both your feet, the saddle might be a tad too low.

There are many pages and videos that describe bike fit -- here's one: http://www.peterwhitecycles.com/fitting.htm