Sciatica only felt at night?

I first had sciatic pain 2 years ago and then again a year ago. The first time I had it I got MRIs that showed a very mild herniation. Each of those bouts took 2-4 months of PT to strengthen the core and improve mobility in a way that completely eliminated pain for the following year or so.

However, I have been injured for the past 3 months (foot & ankle) and I am not supposed to be walking much for another 1-2 months. As such, I’ve been doing a lot of leg/foot/ankle exercises that might be pulling on my sciatic nerve and sitting a lot more than usual.

Unlike my previous bouts with sciatica, this time (for the past 3-4 days) I only feel buttocks pain (no shooting pain down the leg) and mostly only at night (I seem to be able to stretch it out during the day and don’t have issues in my ergonomic chair). Both side-sleeping and back-sleeping (w/ elevated) causes pressure to build up in my buttocks to the point of excruciating pain waking me up typically 4 hrs into the night. Unfortunately because of my feet injuries I can’t sleep on my stomach.

In the past, side-sleeping with a pillow between my legs would’ve kept me pain-free even when standing up / sitting was hell. So I am not sure what is going on here :/ I haven’t been taking any NSAIDs because my stomach was getting sensitive to them from 3 months of daily usage for my other injuries but if some form of slow-release Advil PM could fix this I’m willing to try it for a week or two.

Questions:

• Which specialist should I see first? Primary/Urgent care, sports medicine, neurologist, or ortho (surgeon)? In the past I went for the surgeon but didn't like their pushing injections/surgery without trying conservative treatment first which has worked for me to some degree.
• Any tips for spinal decompression towards temporary relief?
• I have a Leesa hybrid which at the time of purchase felt firm enough and did not bother me on my previous bouts with Sciatica. However, I believe it has softened over time. Would plywood under my mattress firm it up enough?