Please help can't feel babies head in vagina

So I have been carrying my son really really low this whole pregnancy. well about 2 weeks ago he turned breech. 3 days later he turned back to the right position. now I am on early labor and I think he is breech again because I can't feel his head in my vagina and the shape of my belly has changed. usually I have been able to feel his head but I can't anymore. the doctor checked me today I am 2-3 cm dilated and 60% effaced he said the baby is head down and I am at a -1 station. has anyone else had this happen and the baby in fact be head down? I'm So scared to go into labor and have to have a c section because he is breech. It wouldn't worry me as much except I have really fast deliveries and my water broke with all 3 of my other babies.