"What? Still?"

I've been getting those comments lately. I've only recently gone from "semichronic" to "chronic" time-wise, so to a lot of you here I suppose I'm new to this.

I had a herniated disk in my lower back a few months back, and at first it hurt so bad I couldn't take any weight on my right leg without blacking out. I got help and it slowly got (and keeps getting) better, but sitting all day exhausts me and at the end of it I'm always in enough pain for my temper to be short and my mood to be generally bad. I had a lot of sympathy from my friends at first, and I try not to complain because that just doesn't make anything better. My friends, though, who I like a lot and sit and work with ask what's up when I start fidgeting or getting up and walking around a lot just for the sake of it etc. I tell them that it's nothing to worry about, it's just my back hurting, but it's getting better. That's when I get the "What? Still? I thought that was months ago". And yes. Yes it was months ago too. I know it's just... thoughtlessness and inexperience with these kind of things (I'm 23 and most of my friends are my age, +/- 4 years), but it's so frustrating. All it does is remind me that I've been in more or less constant pain for months, and it's going away so slowly.

Sorry for the rant.

Does anyone know of a good answer to these kinds of thoughtless comments that doesn't make me sound like a... well... you know?