rear suspension squeak/creak

I have a 2011 that's developed a squeak/creak on the passenger side rear suspension. You can hear it mostly at low speeds, only occasionally, and not at all above about 25 mph. Handles and brakes fine. Just had an alignment done about 1000 miles ago after purchasing new tires (they weren't able to adjust the rear at all--said everything was seized up but it was within spec. or very close).

I crawled under to look, nothing obviously broken or wrong to my eye. But I'm not a suspension expert so could be missing something.

Any ideas what might be going on? Hoping it's as simple as a shock that needs to be replaced but probably more involved than that.

You think it's safe to drive in this condition until I can figure out what's going on? I may have to break down and take it to the dealer or at least a reputable suspension shop.

Thanks for any help.