back pain and light bleeding month after ERPC

[yeahyeah]

I had an ERPC (D&C) a couple days before christmas...and have had quite light bleeding for the past week, I am thinking it's just first period -- but is quite light and brown and today have quite strong lower back pain on my right side. Has anyone else experienced this? Should I call the hospital? Not sure when to worry and when to just wait it out...