Noticed A Giant Bruise After Slipping From Stairs On Butt. Feeling Sore. Suggestions?

Question: I fell a couple weeks ago I slipped on some stairs and bounced on my butt 2 or 3 steps. It was painful. Within about 20 minutes a knot formed on my left side about the size of a grapefruit. By that night, a giant bruise formed. The next morning, I went to the er and was told my tailbone was not broken after having my tailbone x-rayed. Over the next few days, the bruise got larger and the knot stayed. It has been 2 weeks, it the bruising is better. My chiropractor/acupuncturist said it can take a week or so before a hairline fracture will show. It thought the knot may have gotten bigger. It is still very sore. Today, I went and had a MRI done. It took 40 minutes and I almost did not make it due to lying on a hard surface on my back for that long. The X-ray tech said she could see why it was so painful and allowed me to look at the images. By the way, ice packs really have not helped much. What are your thoughts? Do you think it could be infected? Will it need to be drained?