My back hurts when I lay on my left side, anyone else?

I notice that when I lay on my left side my back starts to hurt mildly right in the middle of my lower back.
I'm 29 weeks and 3 days today.
Would it be bad if I lay on my right side for a little bit?
And should I concerned about the backaches?
I even feel the pains sometimes after I eat. 
And I do feel the baby, right now I layed on my right because I couldn't take the back pain and I feel her wiggling very low in my belly.