Hello , I've had bouts of insomnia , some when working some not,

Could you not ask for a different job with the company your with, say for a week or two ?
I've never programmed , but ive seen a bit of css and it woould melt my brain .
one of the things the sleep people say is avoid computers before bed , do you have long bouts staring at a computer screen ?

Hot baths, quiet room, no big meals before bed ( have a banana ), could you say write down a bit of your next days work stuff early evening , make a list and then you might worry less in the night.
Get your next days clothes, stuff , have a wash down before you got to bed, so you're not rushing around in the morning. Get correct body temp in bed , ambient music.

In UK our employment laws state that if you work at a computer , your allowed to stand and walk around for 5 minutes every hour or so.