Serious Question! TMI

So I have already went to the OB for this and I go back next week for my pap results. But when me and my husband got together when we done the deed it didn’t hurt at all. And now after having my son and plus he is now on the pill cause he has trouble. When we do it now it’s like razor blades inside when we do it missionary. But if we do it from behind it doesn’t hurt at all. This has never happened. Has anyone had the same problem. And we tried pre-seed because where trying to have another baby, and it made me burn and smell. So that’s a no go.