Very achey lower back, legs and feet

[Jinglejanglefish]

Does anyone have any ideas what could be causing this? It has been getting worse over the course of this week but today I have been in quite a bit of pain.

My feet are very achy and uncomfortable to walk on, they do not get better the more I move. I only wear comfortable shoes, and in fact this week I think I have only worn my trainers.

My legs are heavy and achy, makes no difference whether I am up and moving or sitting down, it is a constant dull ache.

My lower back has a pulsing ache, feels quite good to stretch but doesn't actually help it in any way. Again doesnt seem to make a difference whether I move or sit still.

For context I am 28, gave birth seven months ago to DD, do yoga and Pilates as exercise and haven't changed anything recently.

Google keeps bringing up sciatica but I thought that would be a sharp and shooting pain?

I am going to take painkillers and get a hot water bottle, but I'm worried it's a symptom of something nasty.