Funneling and shortening of cervix

I'm currently 25 weeks with boy/girl twins. About 4 weeks ago I had somw bleeding and they did a vaginal ultrasound to check my cervix. It was at 3.8 then and my ob got worried and referred me to a specialist 2 hours away. Two weeks later I went to the specialist and it was at 2.8 and they didn't seem too worried about it. Well I had to go see my regular ob yday and its a 2.5 with funneling and they seem very worried now. Put me on bed rest and gave me Indocin for two days. I'm just worried now and I'm freaking out about every little thing. Has anyone else delt with this?