I'm not much of a bottom, but I do bottom on the rare occasion.
I have a
dildo it's 9 inches long and about average thickness. I find that if I insert this slowly, gently with lots of lube and then just leave it in there for about a half hour before the top arrives then it really helps to loosen me up. It's not a big enough
dildo to totally make my hole gaping or anything like that but I find several advantages to doing this.
First, it loosens me up, so when the top goes to put his cock in me he can slide in pretty easily and it doesn't hurt anywhere near as much.
Second, the
dildo isn't "too big" so there is still some degree of tightness for the top so it feels good to him going in.
Third, using the
dildo beforehand gets my hole used to it, so there's no need for the top to spend the first 5-10 minutes going slow and easy. Instead, it only takes a minute or two and then he can grab on and go at it how he wants, which is what most tops want to do anyway. Trust me, not being able to take him relatively quick is probably going to be a turn-off for him.
The reason you are probably hurting and sore afterwards is most likely because the top is stretching you open too much, too fast. That's how hemmorhoids happen.
I did an experiment with a top friend of mine. He's about 8.5 inches and almost too thick to close my hand around it. I told him about the experiement and he agreed to help me out.
On a Friday night he came over and tried to fuck me, with no preparation beforehand. It hurt like hell and it was a good 20 minutes before he could get more than half of it in me and I don't think he even got all of it in me that night before I had to stop.
The following week on a Tues or Wed (I can't remember) he came over again but I used the
dildo beforehand and left it in me for a half hour before he got here. I left it in right up until he knocked on the door. Within ten minutes of him walking in we went to the bed and he mounted up and I took his entire cock all the way up to his balls and there was no pain at all. He asked if I was okay and told him to just give me all he's got, so he grabbed on and fucked the hell out of me for 45 minutes. When it was over, no pain, no soreness.
Dildos are cheap, give it a try.