Lump on lower back

Hi everyone,

 

I found a fairly large lump in my lower back around a month ago. At that time it didn't hurt me. I mentioned it to my GP who examined me and quite quickly ruled out a fatty lump or a cyst, and so has sent a referral for an ultrasound.
 

Since the appointment with him, I feel the lump has grown in size and I now have pain and discomfort virtually all the time. I'm struggling to sleep because of it. Sometimes the pain goes down my leg, or manifests in my lower back and hip area. I sometimes get pins and needles in my leg and foot on the side of the lump.
 

The lump itself isn't painful, but it feels like that side of my back is taught and stretched because of the lump (if that makes sense?). 
 

I chased the ultrasound with the hospital and have been told it's a 6-8 week wait. I'm going to try and speak to my GP this week but that is easier said than done at my surgery! 
 

I have a few questions I'd love to hear your thoughts on:

- Does what I've described ring alarm bells to anyone? 
- Do you think it's worth paying for a private ultrasound scan to be done sooner? 
- What would you do in my situation? 
 

I'm trying my best to be rational and remind myself that it could be any number of things and is more than likely something innocent, but I am worried.

 

Thanks in advance for any replies.

 

JJ x