felling down and don't know what to do!

I'm 19+2, yesterday I went home from work early as was having slight pains across my stomach, feeling like muscles when done too much exercise only when I cough or sit down. The pain has gone today and I've borrowed a friends Doppler, now I am obese 155kg to be exact. I can not find the baby's heartbeat at all on the Doppler so now I am so worried something is wrong, I havnt felt movement in days either but only feel slight movements every now and then.