(NSFW) How do I loosen it up?

Ok, so my boyfriend and I tried having anal sex two nights ago. Apparently, I’m VERY tight and it was VERY painful. In fact, when I got home and cleaned up, I saw blood on the toilet paper from that area and it’s still sore. He wants to have it again in the future (as do I) but I need to loosen up first. I’m looking into anal plugs and a LOT of lube, but is there another solution until I get the plug?