18 weeks and not feeling my baby anymore?

I know at this stage in the game it's normal to not feel the baby move, but I was feeling he/she move around at least once a day for about a week and now for the past two days I don't think I've really felt anything. I've had terrible gas today (so bad I didn't get out of bed until 4) so maybe there was a little movement but I just thought it was gas? Anyway I know to drink cold water and lay down or drink oj... but please I just want to either have someone say "go to doc." or "you're ok" my husband thinks I'm over reacting (imagine that!). I've heard of buying the heart Doppler thing and I've seen them for rent at baby center but is there anything I could get from say Wal-Mart or Kmart? I don't feel like waiting for a couple days I want to hear it right now! Thanks to anyone who can help.