I have a very large lump on my hip after an injection of clindamycin over a month ago. it hurts. is it normal to last so long and be so big?

Post injection mass: A deep IM injection (into muscle) is associated with the possibility of tissue or vessel damage, some bleeding, and possibly development of a local mass at the site. Some of these masses form "sterile" abscesses during the course of resolution, which are painful, as this one is. Others can actually become a frank abscess filled with fluid which unfortunately requires drainage.