bleeding with twins

I've been bleeding off and on for about 5 days. I did have intercourse on Thursday and started bleeding on Friday night. It has ranged from pink to brown to red back to brown and pink. I don't know what to think. I have called my doctors office and they don't seemed worried at all. (It's only when I wipe and it's not going onto my pantyliner or anything) please help put my mind at ease!!!